Kern River Watershed Coalition Authority …krwca.org/files/Reports/KRWCA Groundwater Trend...MRP)....

Kern River Watershed Coalition Authority

Groundwater Trend Monitoring Work PlanKern County, California • July 1, 2017

Prepared for: Prepared by:


Groundwater Trend Monitoring Work Plan Kern County, California July 1, 2017

Prepared for:

Prepared by:

Certifications

This Groundwater Trend Monitoring Work Plan is signed by the following certified professionals:

Provost & Pritchard Consulting Group

Project Team Provost & Pritchard Consulting Group

Prepared by:

• Linda G. Sloan, PG, CHG

• Timothy J. Jeffcoach

• Velvet Gaston, EIT

• Gavin O’Leary

Reviewed by:

• John Schaap, PE


Reviewed by:

• Nicole Bell, Program Manager

COPYRIGHT 2017 by PROVOST & PRITCHARD CONSULTING GROUP ALL RIGHTS RESERVED

Provost & Pritchard Consulting Group expressly reserves its common law copyright and other applicable property rights to this document. This document is not to be reproduced, changed, or copied in any form or manner whatsoever, nor are they to be assigned to a third party without first obtaining the written permission and consent of Provost & Pritchard Consulting Group In the event of unauthorized reuse of the information contained herein by a third party, the third party shall hold the firm of Provost & Pritchard Consulting Group harmless, and shall bear the cost of Provost & Pritchard Consulting Group's legal fees associated with defending and enforcing these rights.

The Kern River Watershed Coalition Authority (KRWCA) shall have unlimited use of this work product.

Kern River Watershed Coalition Authority • July 2017 i

Table of Contents Abbreviations ............................................................................................................................................... iv

1 Introduction ...................................................................................................................................... 1-1

1.1 Background ............................................................................................................................... 1-1

1.2 Groundwater Trend Monitoring Overview .............................................................................. 1-1

1.2.1 Objectives ............................................................................................................................. 1-1

1.2.2 Implementation .................................................................................................................... 1-1

1.2.3 Reporting .............................................................................................................................. 1-2

1.2.4 Considerations...................................................................................................................... 1-2

1.2.5 Phased Approach ................................................................................................................. 1-2

1.3 Regional Groundwater Trend Monitoring Program ................................................................. 1-2

2 Setting ............................................................................................................................................... 2-1

2.1 General Characteristics ............................................................................................................. 2-1

2.2 Climate ...................................................................................................................................... 2-1

2.3 Geology and Soils...................................................................................................................... 2-1

2.4 Surface Water Quality .............................................................................................................. 2-2

2.5 Hydrogeology............................................................................................................................ 2-3

2.5.1 Water Bearing Zones ............................................................................................................ 2-3

2.5.2 Groundwater Levels & Characteristics ................................................................................. 2-4

2.5.3 General Groundwater Quality .............................................................................................. 2-5

2.5.4 Groundwater Recharge ........................................................................................................ 2-6

2.6 Land Use ................................................................................................................................... 2-7

3 Existing Data ...................................................................................................................................... 3-1

3.1 Additional Studies ..................................................................................................................... 3-1

3.2 Groundwater Depth ................................................................................................................. 3-2

3.3 Groundwater Quality ................................................................................................................ 3-3

3.4 Current Monitoring Networks .................................................................................................. 3-4

4 Groundwater Trend Monitoring Network Design ............................................................................. 4-1

4.1 Purpose ..................................................................................................................................... 4-1

4.2 Approach .................................................................................................................................. 4-1

4.2.1 Phase I – Selection Considerations ...................................................................................... 4-1

Kern River Watershed Coalition Authority • July 2017 ii

4.2.2 Phase II – Specific Well Selection ......................................................................................... 4-6

5 Implementation ................................................................................................................................. 5-1

5.1 Coordination ............................................................................................................................. 5-1

5.2 Depth Measurements ............................................................................................................... 5-1

5.3 Quality Measurements ............................................................................................................. 5-1

5.3.1 Schedule ............................................................................................................................... 5-1

5.3.2 Procedures ........................................................................................................................... 5-2

5.4 Equipment ................................................................................................................................ 5-6

5.4.1 Equipment Cleaning ............................................................................................................. 5-6

5.4.2 Equipment List ...................................................................................................................... 5-6

6 Data Packaging .................................................................................................................................. 6-1

6.1 Reports ..................................................................................................................................... 6-1

6.1.1 Annual Monitoring Report ................................................................................................... 6-1

6.1.2 Electronic Submission .......................................................................................................... 6-1

6.1.3 Other General Order Product Updates ................................................................................ 6-1

6.2 Trend Analysis Methods ........................................................................................................... 6-2

6.2.1 Maps ..................................................................................................................................... 6-2

6.2.2 Graphs .................................................................................................................................. 6-3

6.2.3 Diagrams............................................................................................................................... 6-3

6.2.4 Statistics ............................................................................................................................... 6-3

7 Limitations ......................................................................................................................................... 7-1

8 References ......................................................................................................................................... 8-1

Figures ........................................................................................................................................................ F-1

Kern River Watershed Coalition Authority • July 2017 iii

List of Figures

Figure 1. Map of the Tulare Lake Basin Area ............................................................................................ F-1

Figure 2. KRWCA Boundary Map............................................................................................................... F-2

Figure 3. KRWCA Primary Boundary Generalized Soil Texture Map ......................................................... F-3

Figure 4. Department of Water Resources Designated Groundwater Basins .......................................... F-4

Figure 5. 2007 Depth to Groundwater Contours ...................................................................................... F-5

Figure 6. 2007 Depth to Shallow Groundwater Contours ........................................................................ F-6

Figure 7. 2007 Depth to Groundwater Contours ...................................................................................... F-7

Figure 8. Illustrative Groundwater Elevation Hydrographs ...................................................................... F-8

Figure 9. Average Groundwater Elevation Contours (based on 2000 through 2013 Contours) .............. F-9

Figure 10. Horizontal Hydraulic Conductivity, Unsaturated Zone from CVHM ...................................... F-10

Figure 11. Vertical Hydraulic Conductivity, Unsaturated Zone from CVHM ........................................... F-11

Figure 12. 1990 DWR KRWCA Crop Map ................................................................................................ F-12

Figure 13. 2013 KRWCA Crop Map ......................................................................................................... F-13

Figure 14. Historical DWR (1950-1969) and GAR Nitrate Exceedance Analysis Overlay ........................ F-14

Figure 15. Crop Map and Proposed Monitoring Areas Overlay .............................................................. F-15

Figure 16. Public Water System and Disadvantaged Community (DAC) Groundwater Supply Wells in KRWCA ................................................................................................................... F-16

Figure 17. KRWCA Disadvantaged Community Boundaries .................................................................... F-17

Figure 18. Public Water Supply and Disadvantaged Community (DAC) Well Capture Zones ................. F-18

Figure 19. KRWCA High Vulnerability Area Prioritization Map and Proposed Monitoring Areas Overlay ............................................................................................... F-19

List of Tables

Table 2-1. 1990 KRWCA Irrigated Acres and Percent of Total .................................................................. 2-8

Table 2-2. 2013 KRWCA Commodity Acres and Percent of Total ............................................................. 2-9

Table 3-1. Pesticides Detected in KRWCA Area ........................................................................................ 3-4

Table 4-1. Well Location Considerations and Example Scoring ................................................................ 4-3

Table 4-2. Commodity Acreage ................................................................................................................. 4-4

Table 5-1. Groundwater Sampling Analyses and Schedule....................................................................... 5-2

Table 6-1. Potential Statistical Tests ......................................................................................................... 6-4

Kern River Watershed Coalition Authority • July 2017 iv

Abbreviations AMR ...................................................................................................................... Annual Monitoring Report

bgs ................................................................................................................................ below ground surface

Board ........................................................................... Central Valley Regional Water Quality Control Board

Canal ................................................................................................................................... Friant-Kern Canal

CGQMP ................................................................. Comprehensive Groundwater Quality Management Plan

Coalition ....................................................................................... Kern River Watershed Coalition Authority

COC ............................................................................................................................. constituent of concern

CVHM .......................................................................................................... Central Valley Hydrologic Model

DAC ....................................................................................................................... disadvantaged community

Dairy General Order .............. Waste Discharge Requirements General Order for Existing Milk Cow Dairies

DDW ...............................................................................................................Department of Drinking Water

DO ....................................................................................................................................... dissolved oxygen

DPR ...................................................................................... California Department of Pesticides Regulation

DWR ........................................................................................... California Department of Water Resources

DWSAP .......................................................................... Drinking Water Source Assessment and Protection

EC .................................................................................................................................electrical conductivity

ELAP ................................................................................ Environmental Laboratory Accreditation Program

ET ...................................................................................................................................... evapotranspiration

GAMA ........................................................................... Groundwater Ambient Monitoring and Assessment

GAR ............................................................................................... Groundwater Quality Assessment Report

General Order ............................................................................................. Tulare Lake Basin General Order

GIS ................................................................................................................ Geographic Information System

GPS ........................................................................................................................ Global Positioning System

GQMP ............................................................................................. Groundwater Quality Management Plan

GSA ......................................................................................................... Groundwater Sustainability Agency

GTM .............................................................................................................. Groundwater Trend Monitoring

GTMP................................................................................ Groundwater Quality Trend Monitoring Program

GTMW ........................................................................................ Groundwater Trend Monitoring Work Plan

HVA ............................................................................................................................. high vulnerability area

ILRP......................................................................................................... Irrigated Lands Regulatory Program

Kern River Watershed Coalition Authority • July 2017 v

KCWA .................................................................................................................. Kern County Water Agency

KRWCA ......................................................................................... Kern River Watershed Coalition Authority

MCL ................................................................................................................. Maximum Contaminant Level

MHI....................................................................................................................... median household income

MPEP ......................................................................................... Management Practices Evaluation Program

MRP ........................................................................................................ Monitoring and Reporting Program

NHI .......................................................................................... Nitrate Groundwater Pollution Hazard Index

NOA ............................................................................................................................. Notice of Applicability

NWIS ..................................................................................................... National Water Information System

PLS ..................................................................................................................................... Public Land Survey

Provost & Pritchard ............................................................................ Provost & Pritchard Consulting Group

RWQCB ........................................................................ Central Valley Regional Water Quality Control Board

SGMA ........................................................................................ Sustainable Groundwater Management Act

SSJV ................................................................................................................... Southern San Joaquin Valley

SSJV MPEP .................................. Southern San Joaquin Valley Management Practices Evaluation Program

SWRCB ................................................................................................. State Water Resources Control Board

SWRCB-DDW ........................................... State Water Resources Control Board Division of Drinking Water

TDS ................................................................................................................................ total dissolved solids

TLHR ............................................................................................................... Tulare Lake Hydrologic Region

USDA ............................................................................................. United States Department of Agriculture

USGS ............................................................................................................. United States Geological Survey

Kern River Watershed Coalition Authority • July 2017

Section One: Introduction

Groundwater Trend Monitoring Work Plan

Section One: Introduction Groundwater Trend Monitoring Work Plan

Kern River Watershed Coalition Authority • July 2017 1-1

1 Introduction This Groundwater Trend Monitoring Work Plan (GTMW) has been prepared on behalf of the Kern River Watershed Coalition Authority (KRWCA or Coalition), in response to Waste Discharge Requirements (WDR) General Order R5-2013-0120 (General Order), adopted by the Central Valley Regional Water Quality Control Board (RWQCB or Board) on September 19, 2013. The WDR applies to growers in the Tulare Lake Basin (Figure 1).

1.1 Background

The General Order requires any commercial irrigated land having the potential to discharge to surface water or groundwater to comply with the requirements set forth by the RWQCB. The RWQCB defines irrigated land as “land irrigated to produce crops or pasture used for commercial purposes including lands that are planted to commercial crops that are not yet marketable (e.g. vineyards and tree crops). Irrigated lands also include nurseries, and privately and publicly managed wetlands (excluding the non-irrigated upland habitat associated with managed wetlands)”. Compliance with the General Order requires membership in a coalition (third-party). Alternatively, owners or operators of irrigated land can obtain regulatory coverage under the Individual Discharger General Order (Order R5-2013-0100), or another WDR or conditional waiver of WDRs issued by the RWQCB.

The third-party option allows growers to work together as a group and share resources, minimizing redundant efforts and reducing overall costs. Investigations and evaluations necessary to fulfill regulatory compliance may require extensive expertise and funding, and are more easily undertaken as a group than as individuals.

The KRWCA was authorized by the RWQCB as the third-party group to represent growers within its service area by the Notice of Applicability (NOA) received from the RWQCB on February 4, 2014.

1.2 Groundwater Trend Monitoring Overview

1.2.1 Objectives

Per the General Order, the overall objectives of groundwater trend monitoring are to determine current water quality conditions of groundwater relevant to irrigated agriculture and develop long-term groundwater quality information that can be used to evaluate the regional effects of irrigated agricultural practices. This GTMW will describe the methods that will satisfy the trend monitoring objectives. Specific requirements of the work plan are detailed in the General Order’s Attachment B, Monitoring and Reporting Program (MRP).

1.2.2 Implementation

Key to the work plan is including the rationale for the distribution of trend monitoring wells. The well monitoring network must cover both high and low vulnerability areas, and employ shallow wells, although not necessarily completed in the uppermost zone of first encountered groundwater. Existing wells and monitoring networks may be considered to increase efficiency and reduce costs.



1.2.3 Reporting

Trend monitoring results will include a map of the sampled wells, tabulation of the analytical data, and time concentration charts. They will be included in the third-party’s monitoring report. Monitoring data will be submitted electronically to the State Water Resources Control Board’s (SWRCB) GeoTracker Database and to the Central Valley Water Board. Sufficient data collection will allow the third-party to conduct trend analyses according to methods proposed in this work plan.

1.2.4 Considerations

There is a significant time-lag between the actions on the land surface and the resulting change in the underlying aquifer. In general, greater depths to groundwater correlate with longer lag times in transport time from surface to groundwater. Additionally, correlating changes in irrigated agricultural practices to changes in groundwater quality is further complicated by legacy nitrate residing in the unsaturated zone (from historic agricultural practices), acting as an ongoing source to groundwater.

1.2.5 Phased Approach

This work plan has been prepared as an initial phase (Phase I) of the GTMW to identify monitoring areas for subsequent well selection. A second phase (Phase II) of the work plan will be prepared for submittal after approval of the Phase I work plan. Included in the Phase II work plan will be the sampling implementation schedule and specific well selection. This approach allows the KRWCA to implement groundwater quality monitoring in advance of development of other components of the Irrigated Lands Regulatory Program (ILRP), such as a coordinated regional monitoring effort described in Section 1.3.

1.3 Regional Groundwater Trend Monitoring Program

No single integrated groundwater monitoring network is currently in place in the Central Valley. Consequently, various entities throughout the state collect groundwater quality monitoring data for numerous programs and stakeholders. Programs which require the development, or continuation, of groundwater quality monitoring include government agencies (California Department of Pesticide Regulation (DPR), Department of Drinking Water (DDW), State Water Resources Control Board and United States Geological Survey (USGS)), as well as those created by legislative mandates (SB 1938, AB 3030, and the Sustainable Groundwater Management Act (SGMA)). Other stakeholders in groundwater quality monitoring data include entities regulated by the RWQCB under WDRs, Integrated Regional Water Management Groups, municipalities, and water districts.

The RWQCB has expressed an interest in the development of a regional groundwater monitoring effort to be coordinated with ILRP coalitions and relevant programs. Other RWQCB programs (dairies, landfills, underground storage tanks, etc.) are designed to monitor targeted contaminants, specific to potential point sources, and do not account for regional trends in groundwater quality. As a nonpoint source program, the ILRP is tasked with monitoring region-wide groundwater quality, intended to document varied groundwater conditions to establish trends over time.

As described in GTMWs submitted by other coalitions; coordination, planning, and development of a regional monitoring strategy will require significant effort. Development of a governance structure, monitoring design, and implementation strategy are anticipated to require a minimum of two years,



expected to be completed in 2019. As envisioned by other ILRP coalitions, collaboration is expected to include other agencies, groundwater monitoring groups, and stakeholders. In particular, Groundwater Sustainability Agencies (GSAs) are anticipated to play a key participation role in a regional groundwater monitoring effort. As part of SGMA, GSAs are also required to develop a groundwater monitoring strategy for priority pollutants. However, those monitoring plans are not required to be implemented until 2020, which is three years after some ILRP coalitions were required to submit their trend monitoring plans. Additionally, General Order requirements for the KRWCA do not coincide with timelines for other ILRP coalitions and groundwater monitoring stakeholders.

The KRWCA recognizes the importance of coordinating with other ILRP coalitions, as well as other entities, to develop a regional monitoring program. Implementation of groundwater monitoring programs is costly and complex. A regional effort would be more effective and efficient than multiple programs and agencies working individually. Given the timeline and complexity associated with developing a regional monitoring strategy, the KRWCA proposes to monitor groundwater quality areas, as defined in this GTMW. These monitoring sites could later be incorporated into a regional strategy as it is developed, and the groundwater quality data collected by the KRWCA could help inform regional monitoring decisions, as well as provide a baseline for future monitoring. This approach would allow for the collection of groundwater quality data in advance of the development of a coordinated regional monitoring strategy.


Section Two: Setting


Section Two: Setting Groundwater Trend Monitoring Work Plan


2 Setting 2.1 General Characteristics

The KRWCA boundary (Figure 2) generally coincides with the Kern River Watershed boundary and encompasses 3.5 million acres of land (gross acres), of which approximately 622,200 acres were irrigated (irrigated acres), as defined from 2013 Kern County Agricultural Commissioner data. As of the January 6, 2017 Participant List, 529,493.67 grower reported irrigated acres were registered to KRWCA members. Of the gross acres, approximately 97,600 acres are classified as urban, commercial, or industrial areas. The largest population center within the KRWCA is the City of Bakersfield.

The KRWCA area is separated into the primary boundary, which includes the valley floor, and a secondary boundary that contains very little irrigated acreage. The primary boundary includes approximately 1,023,600 gross acres of land that are within the boundary of the Kern County groundwater subbasin. This includes approximately 619,200 irrigated acres on the San Joaquin Valley floor, as defined in 2013 data. The Upper Kern River Watershed is located almost exclusively within the KRWCA secondary boundary and encompasses approximately 1.5 million acres in the southeastern portion of the San Joaquin Valley.

2.2 Climate

The climate of the KRWCA is considered semi-arid to desert. Potential evapotranspiration (ET), the amount of water evaporated and transpired from healthy grass in a normal year, is 57.9 inches in the southern San Joaquin Valley (Jones, 1999). Potential ET from May to August varies little, less than 5 percent, from year to year (Sanden, 2014a). Effective precipitation, the portion of precipitation that can be beneficially used by crops, averages 3.4 inches in a normal year (KCWA, 1998-2012). As such, local surface water supplies are limited and irrigated agriculture in the region relies on groundwater supplies and imported surface water supplies from the north.

2.3 Geology and Soils

The primary KRWCA area is located mostly within the southern portion of the San Joaquin Valley, a long structural trough filled to a depth of up to 10,000 feet of marine and continental sediments. The continental sediments represent a variety of depositional environments including fluvial, deltaic, lacustrine, and alluvial fan sequences which form an alluvial wedge that thickens to the west across the valley. The secondary KRWCA area extends over a large area of varying geologic and hydrogeologic environments, including upland areas of igneous and metamorphic rock and small valleys filled with continental sediments. The primary portion of the KRWCA area is located almost entirely in the areas of recent alluvium on the floor of the San Joaquin Valley.

Soils on the Kern County valley floor have two general origins that are approximately delineated by the trough of the valley. The eastern alluvial fans were deposited primarily through runoff and sediment transport from the Sierra Nevada, Tehachapi, and Transverse Mountain ranges. These soils are of igneous and metamorphic origin, typically well drained, lower in salinity, and of ideal quality for agriculture. The western alluvial fans originated from Coastal Range sedimentary rock formed on the sea



bottom. This region tends to have more areas with poorly drained soils of relatively marginal quality. Many of the soils on the west side of the valley required some reclamation before crops were grown profitably.

The primary area of the KRWCA can be divided into five main areas relative to soil texture and typical cropping: the Clay Rim, Foothills, Kern Fan, Northern Areas, and Wheeler Ridge/Arvin Edison regions (Figure 3). Soil pH is generally higher in the southern and northwestern areas of the primary KRWCA area. These areas roughly correspond to alluvium from the San Emigdio Mountains and fringes of alluvial fans. High salinity is typical of historic lakebed, swamp and overflow, and alluvial fan margin soils; the combination of high pH and high salinity is found in many of those areas.

Historic lake beds, swamps, and overflow lands consist of slightly acidic lacustrine and alluvial fan margin soils that are formed when fine particles settle out from lake and swamp water. The Kern and Buena Vista historic lake beds are comprised of clay soils with little variation. In particular, the Buena Vista lakebed, though it has silty clay soils at the surface, is underlain by a very thick horizon of clay soil with very low permeability. Surface soils typically have a relatively high saturation percentage (60 to 80 percent), meaning that they hold relatively large amounts of water compared to coarser-textured soils with large pores that drain water more readily.

Generalizations may be made regarding the preferred KRWCA regions and soils for cultivating different crops. In the KRWCA primary boundary most citrus is grown along the eastern side, or Foothills region, where soils are medium-textured. The Foothills regional topography also creates microclimates with fewer incidences of freezing temperatures, conducive to citrus cultivation. Mountain and foothill areas in the northeastern part of the KRWCA boundary are used as rangeland for cattle or sheep and are primarily non-irrigated. Crops such as dryland wheat may be grown in this area. Grapes are typically grown on coarse or medium-textured soils found in the northeastern portion of the KRWCA primary area and in the southern area corresponding to the Kern Fan. In contrast, the heavy (fine-textured) soils of the Clay Rim region are dominated by cotton, wheat, corn and tomatoes. In general, permanent crops have expanded onto various soils that were previously not used to grow trees and vines. Corn and silage has also expanded on various soil types in response to livestock feed demand, primarily in proximity to dairies. See Section 2 in the KRWCA Groundwater Quality Assessment Report (GAR) for additional analysis.

2.4 Surface Water Quality

Only one water body in the KRWCA boundary, Isabella Lake, was listed on the 2012 EPA 303(d) list of impaired water bodies for dissolved oxygen and pH, but no sources are known. Isabella Lake is located within the KRWCA Secondary Area that is primarily a mountainous region with little to no agricultural activities. Agricultural activities largely occur in the Primary Area of the KRWCA on the San Joaquin Valley floor. Districts in the KRWCA generally prohibit agricultural drain water from entering surface water bodies. This effort protects surface water and is believed to contribute to the lack of impaired water bodies in the KRWCA.

The KRWCA searched the DPR Surface Water Database, established through an agreement with the SWRCB in 1997, for sampling locations within Kern County and the KRWCA boundary. The DPR database search for pesticide records in Kern County resulted in finding some exceedances for Chlorpyrifos and Glyphosate, however, none of the exceedances occurred at the monitoring sites within the KRWCA boundary. Most data in the database was taken at locations now within another third-party boundary



(Main Drain Canal in Buena Vista Water Quality Coalition). The results from this search provide further evidence that local districts, agencies, and growers are acting in a manner that is protective of the surface water resource.

2.5 Hydrogeology

The groundwater hydrology of the KRWCA area is considered notable within the Tulare Lake Hydrologic Region (TLHR) due to the groundwater basin configuration, hydrologic stresses, and depth to first-encountered groundwater. As noted in the expert report submitted to the RWQCB, these unique aspects represent spatial disconnects throughout the KRWCA area which must be accounted for in the Groundwater Trend Monitoring Program (GTMP) required by the General Order (Gailey 2013). There is very little information regarding groundwater conditions in the secondary portion of the KRWCA. This is especially true of groundwater level information as there are few groundwater level measurements available and no assessment of regional groundwater patterns has been completed.

The USGS Central Valley Hydrologic Model (CVHM) estimates the vertical and horizontal aquifer parameters of the entire Central Valley, and was used to represent relative aquifer parameter distribution in the Kern County subbasin. The Corcoran Clay is a regionally extensive lowly permeable unit located in much of the San Joaquin Valley (Croft 1972). However, in Kern County the Corcoran Clay is neither considered to have as low permeability, nor to function as a continuous aquitard to vertical flow as it does in the other portions of the Central Valley. The Corcoran Clay is also present at deeper depths than in other areas of the Central Valley (Schmidt and Associates 2006 and Schmidt and Crewdson, personal communication, October 2012).

2.5.1 Water Bearing Zones

There are several delineated groundwater aquifers in the KRWCA primary and secondary areas. The primary source for defined aquifer delineation is the Department of Water Resources (DWR) through Bulletin 118 Interim Update 2016, which defines the extents and describes the recognized alluvial aquifers in California. The entire KRWCA area is in the Tulare Lake Hydrologic Region (DWR, 2016).

The primary portion of the KRWCA area includes parts of four DWR designated basins:

• The Kern County Portion of the San Joaquin Valley Groundwater Basin (Kern County Subbasin, No. 5-22.14);

• The Cummings Valley Groundwater Basin (No. 5-27);

• The Tehachapi Valley West Groundwater Basin (No. 5-28); and,

• The Brite Valley Groundwater Basin (No. 5-80).

Locations of these groundwater basins are shown on Figure 4.

The majority of the primary portion of the KRWCA area is within the Kern County Subbasin, which is the southern-most portion of the San Joaquin Valley Groundwater Basin, as defined by DWR. The Kern County Subbasin is included in the CVHM. The USGS generally used the DWR delineations of groundwater basins in the Central Valley in the development of the active area of the CVHM.

The predominant water bearing material in the Kern County Subbasin is relatively young (Pliocene to Holocene) continentally derived unconsolidated alluvium, with marine derived unconsolidated alluvium



of similar age present in the western and southern portions of the Subbasin (Wood and Dale, 1964; Dale et al. 1966; Croft, 1972; and Page, 1986).

As outlined by the DWR, the Kern Subbasin water bearing zones are generally comprised of the following formations:

• Olcese Formation: Primarily sand, ranging from 100 - 450 feet (ft) thick, supplies drinking water in the northeastern portion of Kern County where the formation occurs as a confined aquifer;

• Santa Margarita Formation: Coarse sand, ranging from 200 - 600 ft thick, supplies drinking water in the northeastern portion of Kern County where the formation occurs as a confined aquifer;

• Tulare Formation: Comprised of clays, sands, and gravels, up to 2,200 ft thick, derived from the Coastal Range, moderately to highly permeable and yielding moderate to large water quantities, includes the Corcoran Clay Member;

• Kern River Formation: Includes poorly sorted lenticular clay, silt, sand, and gravel derived from the Sierra Nevada, ranging from 500 – 2,000 ft thick, moderately to highly permeable and yielding moderate to large water quantities, includes the Corcoran Clay Member;

• Older Alluvium/Stream and Terrace Deposits: Loosely consolidated lenticular deposits of clay, silt, sand, and gravel, 250 ft thick, yielding large water quantities; and,

• Younger Alluvium/Flood Basin Deposits: Stratified and discontinuous clay, silt, sand, and gravel beds, up to 150 ft thick, permeability varies with fine grained percentage, as with deposits underlying historic Buena Vista and Kern Lakes (DWR 2003).

Shallow groundwater areas identified and mapped by the Kern County Water Agency (KCWA) roughly correlate to areas of low permeability soils in and around the Buena Vista and Kern Lake beds in the southern portion of the Subbasin, and within the western portion of the Semitropic Water Storage District. The KCWA has been tracking the presence of these shallow groundwater areas since 1976, and the extent of the area has generally increased over that period (KCWA, 2011). While the shallow groundwater areas are contoured separately from the unconfined aquifer, there is no indication that shallow groundwater is actually a completely separate and distinct water body.

2.5.2 Groundwater Levels & Characteristics

KCWA prepares two annual depth to groundwater maps. There is one annual spring map showing depth to groundwater in the unconfined aquifer throughout the Kern County Subbasin (Figure 5), and another showing depth to water in shallow groundwater areas (Figure 6), where water is present at less than 20 feet below ground surface. Since the shallow groundwater areas do not appear to be separate and distinct from the rest of the subbasin, the two depth to groundwater contour datasets are combined using geographic information system (GIS) tools for the assessment of unsaturated zone thickness.

The thickness of the unsaturated zone varies over time and space in the Kern County Subbasin in response to temporal and geographic variation in recharge and groundwater use. The KRWCA assessed variations in unsaturated zone thickness by comparing groundwater elevation contour maps from multiple years to one another.

Based on annual spring groundwater elevation contours prepared by KCWA for 2000 through 2013 (KCWA 2014), the highest groundwater elevations in the period were in the spring of 2007 (wet period)



and the lowest occurred in the spring of 2013 (dry period). The spring 2007 groundwater elevation contours are shown on Figure 7. The 2007 wet period unconfined aquifer depth to groundwater ranges from less than 50 ft below ground surface (bgs) to over 700 ft bgs. The deepest groundwater depths occur in the southern portion of the KRWCA primary area. The 2013 dry period depth to water contours are similar but show that groundwater is generally 30 to 80 ft lower. Groundwater elevations in 2007 were highest near the Kern River and the associated groundwater banking operations. The lowest groundwater elevations during this period are in the northwest portion of the subbasin. Selected illustrative hydrographs showing a range of local groundwater elevation trends throughout the KRWCA primary area are shown on Figure 8.

Since the spring 2007 depth to water data corresponds to the highest groundwater elevations in the period of study, it also corresponds to the shallowest depth to groundwater and thinnest unsaturated zone. This condition was chosen to characterize the unsaturated zone for the hydrogeologic evaluation because it is conservative with regard to travel time from ground surface to first encountered groundwater.

As described above, the contours for each spring 2007 depth to water condition were converted to surfaces using GIS tools and then combined. Where the two surfaces overlapped, the shallower depth to water value was used. This resulted in a single dataset representing a conservative depth to first encountered groundwater in the entire subbasin.

The hydraulic conductivity parameters from the CVHM groundwater model were extracted for the unsaturated zone throughout the primary KRWCA area. The combined depth to groundwater surface described above was interpolated to the CVHM grid to identify the depth of the unsaturated zone. The distribution of these hydraulic conductivity values is shown on Figure 10 and Figure 11. These unsaturated hydraulic conductivity values represent the best available information regarding relative permeability of the unsaturated zone throughout the Kern County Subbasin portion of the KRWCA primary area.

Given the significant variations in groundwater elevations that occur throughout the Kern Subbasin in response to variations in hydrologic conditions, no single groundwater elevation surface should be taken to be representative of groundwater flow directions. Therefore, a combined groundwater elevation surface was generated to represent trends in groundwater elevation and flow directions throughout the Subbasin, found on Figure 9. These flow directions show that average groundwater flow north of the Kern River is generally towards the north and center of the Subbasin, focused on low average elevations in the north.

2.5.3 General Groundwater Quality

The primary portion of the KRWCA area includes the majority of the Kern County Subbasin of the San Joaquin Groundwater Basin, which is an inland groundwater basin with no significant outflow. In the Tulare Lake Basin and areas immediately adjacent to it, there is a tendency for salts to accumulate, due to almost no percolation (frequently upward groundwater gradients) and evapoconcentration. Localized areas of elevated salinity can develop upgradient where inadequate leaching, flushing, and outflow occur due to local drainage impairments such as poorly drained soil or limited surface drainage toward the historic Tulare Lake.

Shallow zones in the eastern subbasin are primarily characterized as containing calcium bicarbonates and increasing in sodium concentrations with depth. This trend shifts from east to west, with west side



water primarily containing sodium sulfate to calcium-sodium sulfate. Shallow groundwater in the western region is characterized by high TDS, sodium chloride, and sulfate which is problematic for agricultural uses. Arsenic levels in groundwater are often associated with lakebed deposits (DWR 2003).

Groundwater chemistry and quality, including concentrations of constituents of concern (COCs), may vary based on depth within the same region. Additionally, wells with damaged or improperly constructed surface seals, or no seals, may provide vertical preferential pathways for vertical migration between aquifers. This happens through the materials filling the annular space between the well casing and the formation walls. Additionally, wells with perforated intervals emplaced across, or both above and below, semi- or confining layers may also provide a vertical preferential pathway. When aquifers of differing water qualities are connected in this manner, water quality may be affected in both aquifers.

Refer to Section 3.4 for additional information on groundwater quality in the KRWCA area.

2.5.4 Groundwater Recharge

Groundwater recharge is the sum of the hydrogeologic processes by which water percolates into a groundwater aquifer, a function of available water and permeable ground surfaces. Permeability of ground surfaces vary with the varying soils and surficial geology. As mentioned above, unsaturated hydraulic conductivity values represent the best available information regarding relative permeability of the unsaturated zone throughout the Kern County Subbasin portion of the KRWCA primary area. The regional distribution of hydraulic conductivity values for the unsaturated zone was discussed in Section 2.5.2.

Natural recharge, a function of precipitation, ET, and soil moisture holding capacity, is limited in the primary area. In the secondary area natural recharge is dominant but difficult to estimate because of variable precipitation/runoff, limited extent of unconsolidated material, and predominance of fractured bedrock groundwater.

Agricultural return flow is the water that runs off crop land and/or percolates past the root zone in excess of the crop needs, or root zone water holding capacity. Agricultural return flow is primarily a function of irrigation efficiency, effective precipitation, and management. Municipal return flow results from precipitation and water applied to the ground surface in municipal settings that exceeds evaporation, consumptive use, and root zone water holding capacity, or percolation from stormwater detention basins. Treated wastewater is regulated by the RWQCB under specific individual WDRs and waste discharge permits. Recharge from septic systems is significant in the KRWCA, but is not measured or estimated. Recharge from wastewater generated by food processing, confined animal facilities, and other industries may also be significant, but are generally regulated under WDRs.

The Friant-Kern Canal (Canal) flows from north to south near the eastern edge of the valley floor, providing irrigation water for several federal water contractors. At the southernmost point on the Canal, it interties with the Kern River. During high flow events, excess Friant-Kern water is diverted into the Kern River channel in Bakersfield. The water is used for groundwater recharge in the Kern River channel or re-diverted downstream into large groundwater recharge facilities on the Kern River Fan (e.g., Kern Water Bank, Pioneer Banking Project, and City of Bakersfield’s 2800 Acres).

Enhanced recharge and banking is performed in the KRWCA area by multiple water agencies through mechanisms such as recharge ponds, canal seepage as water is conveyed, and seepage from reservoirs. In-lieu recharge activities that displace groundwater use by providing surface water, in-lieu of pumping



groundwater, are also a significant recharge management practice in the region. Canal seepage is generally high-quality water, and managed recharge is considered to have an overall positive benefit to groundwater quality in the KRWCA area. There are a number of enhanced groundwater recharge projects in the KRWCA area. Additional analysis and mapping of these projects is presented in Section 8 of the KRWCA GAR.

Recharge areas are a “primary” net benefit to groundwater quantity, and high-quality source water may provide a “secondary” net benefit by diluting the concentrations of groundwater constituents. Major groundwater recharge sources in the KRWCA area generally have lower concentrations of nitrate and salinity than the receiving groundwater aquifer. However, minor recharge sources may have higher concentrations of nitrates and salinity, and could negatively impact groundwater quality.

2.6 Land Use

Information on land use within the KRWCA was developed from the Kern County Agriculture Commissioner, U.S. Department of Agriculture (USDA), and DWR. Kern County has the second largest crop-based economic value of agricultural counties in the state and nation, producing over 250 crops; including 30 types of fruit and nuts, over 40 varieties of vegetables, over 20 field crops, lumber, nursery stock, livestock, poultry and dairy products (USDA, 2014). Reviewing land use data within the KRWCA primary boundary illustrates the change in crops and irrigation systems that have occurred in recent history. See Figure 12 for a review of the KRWCA historical (1990) cropping distribution, referencing the DWR crop database, and Figure 13 for 2013 cropping distributions as documented by the Kern County Agriculture Commissioner.

The predominant KRWCA crop in 1990, from the DWR crop database (DWR, 2016b), was cotton. Cotton accounted for about 236,000 irrigated acres (aerial extent)—over one third of all irrigated acres. Cotton, field crops (small grains, hay and forage), alfalfa, and truck crops (vegetables, melons and berries) made up almost 80 percent of the cropped irrigated acreage. However, almond, grape, and citrus were also significant individual crops at this time. Table 2-1 lists the various KRWCA crops in 1990 and respective percent of total irrigated acreage.



Table 2-1. 1990 KRWCA Irrigated Acres and Percent of Total

1990 KRWCA Irrigated Acres and Percent of Total

Crop 1990 Irrigated Acres % of Total Alfalfa 96,302 14.09% Almond 62,254 9.11% Carrots 7,304 1.07% Citrus 32,292 4.72% Corn 6,125 0.90% Cotton 236,853 34.66% Field Crop 102,334 14.97% Fruit Tree 11,604 1.70% Grapes - Table and Wine 66,681 9.76% Nut Tree 2,198 0.32% Pistachios 3,111 0.46% Range/Pasture 4,199 0.61% Silage/Forage 2,520 0.37% Truck Crop 49,675 7.27%

Total: 683,451 100%

For 2013, the Kern County Agriculture Commissioner spatial crop database provides land use data in commodity acres, which may include multiple counting of double and triple cropped irrigated acres (County of Kern Agriculture and Measurement Standards, 2014). Table 2-2 lists the commodity acreage and percentage of total cropped area in 2013. In 2013, 466,347 irrigated acres were single-cropped while 152,894 irrigated acres were multi-cropped. Cotton acreage fell to approximately 38,000 acres in 2013 (less than 20 percent of 1990 acreage). In contrast, almond and pistachio acreage increased from 62,000 to 162,000 acres and 3,000 to 44,000 acres, respectively. Corn also increased from 6,000 acres to 40,000 acres, replacing some alfalfa acreage, and much of the range and pasture acreage.



Table 2-2. 2013 KRWCA Commodity Acres and Percent of Total

2013 KRWCA Commodity Acres and Percent of Total

Crop 2013 Commodity Acres % of Total Alfalfa 76,220 9.45% Almond 162,813 20.20% Carrots 37,654 4.67% Citrus 56,732 7.04% Corn 39,496 4.90% Cotton 38,033 4.72% Field Crop 130,554 16.19% Fruit Tree 15,140 1.88% Grapes - Table and Wine 87,359 10.84% Nut Tree 1,535 0.19% Pistachios 43,565 5.40% Range/Pasture 375 0.05% Silage/Forage 667 0.08% Truck Crop 116,010 14.39%

Total: 806,153 100%

Overall, the proportion of permanent crops grown in Kern County has increased significantly in the past 20 years, and in nearly all cases, they are planted with highly efficient drip and/or micro spray irrigation systems. Widespread conversion from gravity irrigation systems to pressurized systems has been accompanied by an increasing use of fertigation, where liquid fertilizer is delivered to the crop in irrigation water. Pressurized systems allow for precise fertilizer delivery, although fertigation is used in some surface irrigation systems as well. Irrigation water and delivery infrastructure are currently the most expensive components of agricultural production in Kern County, driving irrigation efficiency. Growers are also generally motivated to employ efficient nutrient management because fertilizer additions represent another large expense.


Section Three: Existing Data


Section Three: Existing Data Groundwater Trend Monitoring Work Plan


3 Existing Data 3.1 Additional Studies

There have been multiple studies documenting the major sources of nitrogen flux to groundwater in California. Harter et al. (2012) published a report for the State Water Resources Control Board Report to the Legislature titled “Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater.” As stated in the Executive Summary, this report was a requirement of Senate Bill SBX2, promulgated in 2008 to

“…improve the understanding of the causes of nitrate groundwater contamination, identify potential remediation solutions and funding sources to recover costs expended by the state to clean up or treat groundwater, and ensure the provision of safe drinking water to all communities.”

This report also has eight associated technical reports that cover nitrogen sources of loading to groundwater, source reduction, groundwater quality, groundwater remediation and management for nitrate, water treatment and alternatives, and regulatory and funding options for nitrate management. In general, Harter et al. (2012) found that agricultural fertilizers and animal wastes applied to cropland are the largest regional sources of nitrate in groundwater, and that other sources such as septic tanks can be locally relevant. It also states that nitrate problems will likely worsen for several decades as legacy nitrogen continues to migrate to groundwater. These reports and additional information are available at http://www.groundwaternitrate.ucdavis.edu. The titles of the reports are listed below and the full citations are in the references section of this GTMW:

• Main Report – Addressing Nitrate in California Drinking Water (Harter et al., 2012)

• Technical Report 1: Project and Technical Report Outline (Harter and Lund, 2012)

• Technical Report 2: Nitrogen Sources and Loading To Groundwater (Viers et al., 2012)

• Technical Report 3: Nitrogen Source Reduction to Protect Groundwater Quality (Dzurella et al., 2012)

• Technical Report 4: Groundwater Nitrate Occurrence (Boyle et al., 2012)

• Technical Report 5: Groundwater Remediation and Management for Nitrate (King et al., 2012)

• Technical Report 6: Drinking Water Treatment for Nitrate (Jensen et al., 2012)

• Technical Report 7: Alternative Water Supply Options for Nitrate Contamination (Honeycutt et al., 2012)

• Technical Report 8: Regulatory and Funding Options for Nitrate Groundwater Contamination (Canada et al., 2012)

Several other reports and ongoing activities exist to understand the impact irrigated agriculture in California has on groundwater quality, and the correlation with intrinsic hydrogeologic factors. These reports (CDFA, 2013; Rosenstock et al., 2013) describe actions to address nutrient management and water quality and evaluate the current state of knowledge on nitrogen use and fertilization rates by



agricultural crops. The Conclusions of the Agricultural Expert Panel report (Burt et al., 2014) addresses 13 questions posed by the State Water Resources Control Board related to topics of groundwater vulnerability, management practices, and reporting requirements in the context of the ILRP. The Southern San Joaquin Valley Management Practices Evaluation Program (SSJV MPEP) Work Plan (SSJV MPEP Committee, 2016) describes strategies to understand the impact of various agricultural management practices on groundwater quality. It includes characterization of various factors of the SSJV, such as cropping, soils, irrigation, climate, geology, and groundwater, in addition to nitrogen source quantification. Land IQ prepared a literature review for the SSJV MPEP (Land IQ, 2015). The SSJV MPEP will utilize available literature to understand management practices that are generally known and accepted to be protective of groundwater quality, and will focus early grower outreach on these practices. Existing literature and limited focused field studies will be used to calibrate landscape-level modeling, using the Soil and Water Assessment Tool (SWAT), to understand differences in impact on groundwater quality between various management practices. The SSJV MPEP is pursuing a field study on cropped fields with sandy soils and shallow groundwater (rapid time of transit) to demonstrate the connection between management of the crop root zone to groundwater quality and corroborate modeled findings. The California Nitrogen Assessment (Tomich et al., 2016) is the first comprehensive accounting of nitrogen flux in California. It states that agriculture is the largest source of nitrogen imports to California, and is also the largest source of nitrogen leaching to groundwater. Of the total mass of nitrogen that is leached to groundwater, one-third is removed via "pump and fertilize," drinking water extraction, or aquifer denitrification. The assessment states that a substantial reduction in nitrogen leaching would be required to stop nitrogen accumulation in groundwater. The assessment will be refined as updated information becomes available, and it is intended to be a baseline status of nitrogen flux in California. Although there are publications on agriculture’s impact on groundwater quality and the correlation with intrinsic properties of the landscape, much of the information such as Harter et al. (2012) and Tomich et al. (2016) is at the landscape scale and utilizes many assumptions that may not be representative of the conditions found within the KRWCA or on a field level. However, the KRWCA closely follows these studies and all other research projects on the relationship between agricultural management practices and groundwater quality. The KRWCA utilizes the available scientific knowledge to inform all aspects of its ILRP. As the ILRP proceeds, the available literature and the information that is developed through the SSJV MPEP, the GTMW, and other aspects of the program will be used to inform and guide the program, as appropriate.

3.2 Groundwater Depth

Groundwater is present in both the primary and secondary portions of the KRWCA area. Groundwater level measurements have been collected in the primary portion of the KRWCA area for many decades by multiple parties, including the large scale long term monitoring programs of the California Department of Water Resources (DWR), United States Geological Survey (USGS), and Kern County Water Agency (KCWA). These monitoring programs have not included groundwater level data collection in the secondary area, so information regarding groundwater elevations and flow directions in the secondary portion of the KRWCA area is not available.



The primary KRWCA area is comprised of the DWR designated Kern County portion of the San Joaquin Valley Groundwater Basin (Kern County Subbasin), as well as portions of the Cummings Valley, Tehachapi Valley West, and Brite Valley Groundwater Basins (DWR 2016a). Groundwater level data is only available for the Kern County Subbasin part of the KRWCA primary area. The principal source of regionally extensive groundwater level information within the Kern County Subbasin is the KCWA. The KCWA has long collected and compiled groundwater level data from throughout the subbasin, including data from other agencies, and prepares annual depth to groundwater and groundwater elevation contour maps from these data, as discussed in Section 2.5.2. The existing data presents a good functional representation of the groundwater level conditions and trends, if any, within the KRWCA primary area.

There is very little information regarding groundwater conditions in the secondary portion of the KRWCA. This is especially true of groundwater level information. Since groundwater in most of the secondary area occurs in fractured bedrock, there is not a consistent groundwater surface between geographically separate portions of the secondary area. In addition, there are very few groundwater level measurements available for the secondary area and no previously completed assessment of regional groundwater patterns has been completed.

3.3 Groundwater Quality

Nitrate (NO3–) is a naturally occurring form of nitrogen that can be transformed from atmospheric nitrogen or decomposing organic matter. Naturally occurring nitrate concentrations generally do not exceed 20 milligrams per liter (mg/L) nitrate as nitrate in groundwater (Hounslow, 1995). Nitrate can also be found in groundwater as a result of application of nitrogen fertilizers in irrigated agricultural and landscaped areas, runoff from feedlots or dairies, wastewater and food processing waste percolation, and leachate from septic system drainfields (Harter et al., 2012). In the KRWCA area, the highest nitrate concentrations are located on the edges of the primary area, specifically in the eastern portion, the very southern portion and a small area located outside the primary area boundary in the upper elevations to the east. DWR completed a nitrate evaluation of the San Joaquin Valley in 1970, which plotted maximum nitrate concentrations found by Public Land Survey (PLS) sections in Kern County from records for 1950 through 1969 (DWR, 1970). Spatial analysis of the nitrate impacts indicates that much of the nitrate exceedance area was already above the maximum contaminant level (MCL) in 1970. This correlation is particularly evident throughout the eastern rim and southwestern portion of the KRWCA primary region. Figure 14 provides an overlay of the nitrate impacted area identified in the KRWCA’s GAR and the historical DWR findings. As irrigated agriculture began in the late 19th century and regional travel times range from decades to centuries, it is plausible to deduce that the impacts recorded in the 1970 DWR report may be the result of early, inefficient, agricultural practices and/or natural sources.

Sources of pesticides in the groundwater include applications to agricultural and lawn and garden areas, golf courses, and road or railway weed control. Concentrations in most water bodies are low, generally ranging from 10–5 to 10–3 mg/L (Chapman and Kimstach, 1992 and Montgomery, 1993). There are at least 146 individual chemical compounds that indicate pesticides in water quality samples. Table 3-1 lists pesticides detected in the KRWCA area. Pesticide impacted groundwater in the KRWCA area was identified in the GAR by an exceedance of the respective MCL for detected constituents. The detections



and exceedances are located in disparate locations of the primary portion of the KRWCA area, and do not appear to have a spatial trend.

Table 3-1. Pesticides Detected in KRWCA Area

Pesticides Detected in KRWCA Area

1,2 Dibromoethane (Edb) Cyanazine Methiocarb

1,2 Dichlorobenzene (1,2-Dcb) Deethylatrazine Methoxychlor

1,2 Dichloropropane (1,2 Dcp) Diazinon Methyl Bromide (Bromomethane)

1,2-Dibromo-3-Chloropropane (Dbcp) Dicamba (Banvel) Metolachlor

1,3 Dichloropropene Dichlorprop Metribuzin

2,4,5-Tp (Silvex) Dieldrin Molinate 2,4-Dichlorophenoxyacetic Acid (2,4 D) Dimethoate Naphthalene

Acenaphthene Dimethyl Phthalate Norflurazon

Acetone Di-N-Butylphthalate Oxamyl

Alachlor Dinoseb Paraquat

Aldicarb Diuron Penoxalin

Aldicarb Sulfone Endothall Picloram

Atrazine (Aatrex) Endrin Prometon

Bentazon Eptc Prometryn

Bromacil Glyphosate (Round-Up) Propachlor (2-Chloro-N-Isopropylacetanilide)

Butachlor Heptachlor Simazine

Carbofuran Heptachlor Epoxide Thiobencarb

Carbon Disulfide Hexachlorobutadiene Xylenes (Total)

Carbon Tetrachloride Hexazinone

Chlordane Lindane (Gamma-Bhc)

3.4 Current Monitoring Networks

There are many local agencies/entities that historically and currently conduct groundwater monitoring in the KRWCA area. This monitoring includes groundwater quality and/or groundwater elevation data collection. The wells used in these monitoring programs are spread throughout most of the KRWCA area.

Of the known monitoring locations, there are 7,331 locations in the primary area (1,173 from SWRCB-DDW, 3,126 from DWR, 29 environmental monitoring wells, 2,150 from KCWA, and 853 water supply wells), and 1,327 in the secondary area (730 from SWRCB-DDW, 287 from DWR, 1 environmental monitoring well, 217 from KCWA, and 92 water supply wells).



The existing monitoring programs provide good groundwater elevation and groundwater quality data coverage for the primary portion of the KRWCA and fair coverage of the secondary portion. These plans are more consistently designed to collect groundwater elevation data, but groundwater quality data is also collected, in some cases.

Readily available well construction information associated with the existing monitoring programs has been insufficient to comprehensively evaluate depth specific groundwater quality in the KRWCA area. This creates a significant data gap in characterizing agriculture’s effect on shallow water quality.


Section Four: Groundwater Trend

Monitoring Network Design


Section Four: Groundwater Trend Monitoring Network Design Groundwater Trend Monitoring Work Plan


4 Groundwater Trend Monitoring Network Design

4.1 Purpose

The primary purpose of the groundwater trend monitoring network design in the KRWCA area is to establish a network of wells that will provide regional representation of long-term groundwater quality trends as they relate to potential influences from irrigated agriculture and regional changes to agricultural practices.

Design of the GTMP takes into account multiple considerations. These include the types of agricultural crops grown within the KRWCA area, particularly those with the most irrigated agricultural acreage. Additionally, it considers hydrogeologic conditions, groundwater flow direction in relation to DACs, and significant recharge areas as determined in the GAR.

4.2 Approach

As discussed in Section 1.2.5 the network design will be completed in two phases. The initial phase will outline the considerations for monitoring areas and wells. The second phase will weigh candidate wells based on the aforementioned considerations and owner cooperation in order to finalize the well network. It will also include the sampling implementation schedule.

4.2.1 Phase I – Selection Considerations

4.2.1.1 Well Depth

Attachment B to the General Order lists criteria for implementing the Groundwater Quality Trend Monitoring Program. One such requirement is to employ shallow wells. This will allow for monitoring what approximates first encountered groundwater, which better indicates changes in groundwater quality from surface activities at the earliest possible time. First encountered groundwater also “more readily allows identification of the area from which water entering a well originates,” according to the General Order. As a result, the final wells chosen will be verified as relatively shallow wells considering the depth to groundwater in each monitoring subarea.

4.2.1.2 Well Type

Based on the requirement to sample relatively shallow groundwater, it is anticipated that domestic wells will comprise a majority of the monitoring network. Irrigation and other production wells would likely pull water from too deep in the aquifer and may not be appropriate for this program.

Temporal continuity is also better assured with domestic well sampling as, in the event the well becomes unusable, there is a higher likelihood that a replacement well in the same approximate location would be installed. Thus, future trend monitoring in that area could continue relatively undisturbed. With other types of wells (i.e., irrigation and monitoring wells for release sites) there is less likelihood that a damaged or dry well would be replaced with a similar well in the same area, which would be a disruption to continued trend monitoring.



Additionally, several potential issues exist with the use of monitoring wells associated with other regulatory programs. These programs are typically instituted where water quality issues from point-sources may manifest. This makes it difficult to discern which water quality issues are potentially attributable to farm practices and not to the site selected.

While other wells may be considered, domestic style wells will be preferentially selected over deeper irrigation/production wells or monitoring wells installed for other regulatory programs.

4.2.1.3 Well Construction

Well construction characteristics are critical considerations to identify suitable wells for the trend monitoring network. Important well construction information includes well depth, perforated intervals (depths to the top and bottom of perforations), and seal presence, depth, and material. Maintaining well construction information will allow GTMP data to be assessed with respect to water bearing zones, and provide additional information on the vertical distribution of constituent concentrations.

4.2.1.4 Well Distribution General monitoring locations will be assigned based on Public Land Survey townships within the KRWCA. Long-term groundwater monitoring will occur within each township that passes the vetting process to evaluate ongoing nitrate patterns and trends in groundwater. This may include PLS sections of the KRWCA that do not currently have groundwater quality monitoring. These areas represented data gaps in the initial analysis of nitrate impacts within the KRWCA region conducted in the GAR. The additional data will be employed to update the high vulnerability analysis to be provided in the GAR 5-year update. A number of the regions which lack data are located in areas without usable groundwater or wells, including, but not limited to, the Buena Vista Lake area. These locations will not be included, as only existing wells will be used. In order for a township to be considered for well selection, groundwater must be present and at least 20% of the township must be used for irrigated agriculture of KRWCA members.

4.2.1.5 Number of Wells

One to three wells per township will be required to accomplish the objectives of the GTMP. This is sufficient to assess current water quality conditions of groundwater, as well as monitor composite regional effects of irrigated agriculture over the long term.

The specific number of wells chosen per township is a function of each area’s characterization by distribution of irrigated agriculture, contribution to recharge, and HVA prioritization. The following section outlines these considerations and how they impact well density per township.

As a measure of redundancy, backup wells will be selected to ensure continuity of the trend monitoring program. When the number of wells that pass the suitability vetting process in the township is less than the optimal number for the program, all potential wells will be selected.

4.2.1.6 Well Location

Well location is considered one of the most important factors to determine well suitability for inclusion in the GTMP. The optimal density of long-term monitored wells in each township was determined by monitoring priority. Rationale for this priority considered:



• The variety of agricultural commodities produced within the KRWCA’s boundaries (particularly those commodities with the most irrigated agricultural acreage);

• The areas identified in the GAR as contributing significant recharge to urban and rural communities where groundwater serves as a significant source of supply; and,

• The conditions discussed/identified in the GAR related to the vulnerability prioritization, and high vulnerability areas assigned by the RWQCB’s Executive Officer.

Each consideration was assigned a range of scores and relative weight. Then, each township was assessed for the considerations and scored according to the given scale. The scores were multiplied by the related weights, producing the weighted score. A sum of the weighted scores, applying standard rounding rules, yielded the number of wells to be selected in the township. Thus, all considerations for the number and locations of monitored wells were duly accounted for. If less than 20% of a township is used for irrigated agriculture of KRWCA members, then no wells were selected for the township, regardless of weighted score. This precludes an overrepresentation of townships with a minute quantity of irrigated agriculture. Similarly, a maximum of one monitored well was selected for the townships along the base meridian boundary due to their reduced area. Refer to Table 4-1, below, for an example of this index method. Priority considerations and scoring method are detailed in the following table, as well as the subsequent sections.

Table 4-1. Well Location Considerations and Example Scoring

Well Location Considerations

Considerations (Score Criteria) Weight Score Weighted

Score

Agricultural Variety 3 = predominant crop in top third of crops in total commodity acreage 2 = predominant crop in middle third of crops in total commodity acreage 1 = predominant crop in bottom third of crops in total commodity acreage 0 = < 20% of township is KRWCA irrigated agriculture

0.35 2 0.7

Vulnerability Prioritization 3 = GAR Tier I (high) 2 = GAR Tier II (medium) & assigned by RWQCB 1 = GAR Tier III (low) 0 = not designated as HVA *choose highest priority located within the township

0.65 3 1.95

Total: 1 2.65

Variety of Agricultural Commodities

In selecting the number of wells per township, efforts were made to ensure that the most prominent crop types are adequately represented in the trend monitoring network design.

If the predominant crop in a township is within the top third of crops ranked in total commodity acreage for the coalition, then the township received the highest score, three, in this category. If the



predominant crop ranks in the middle or bottom third, then the township received a score of two or one, respectively. Refer to Table 4-2, below, for crop rankings and resultant scores.

Table 4-2. Commodity Acreage

Crop Rankings

Crop 2013

Commodity Acres

% of Total Cropped Area

Crop Rank Order Score

Almond 162,813 20.20% 1 3 Field Crop 130,554 16.19% 2 3 Truck Crop 116,010 14.39% 3 3 Grapes - Table and Wine 87,359 10.84% 4 3 Alfalfa 76,220 9.45% 5 2 Citrus 56,732 7.04% 6 2 Pistachios 43,565 5.40% 7 2 Corn 39,496 4.90% 8 2 Cotton 38,033 4.72% 9 2 Carrots 37,654 4.67% 10 1 Fruit Tree 15,140 1.88% 11 1 Nut Tree 1,535 0.19% 12 1 Silage/Forage 667 0.08% 13 1 Range/Pasture 375 0.05% 14 1

Total: 806,153 100%

As a result, townships with crop types representing the largest acreage were weighted more heavily than areas with minor crop types with respect to monitoring network coverage. Thus, more proposed monitoring areas were selected from crops with the largest acreage (e.g., almonds, field and truck crops). A crop map with overlaid number of proposed monitored wells is presented as Figure 15.

The variety of agricultural commodities in a township accounted for 35% (weight of 0.35) of the total consideration for number of wells indicated in our methodology. Similarly, agricultural variety is one of three factors that comprise the rationale for monitoring priority according to the Order.

Recharge to Community Supplies

The cornerstone for the importance of groundwater quality is the potential impact to the population’s health. Therefore, it is essential to select wells that represent the areas identified in the GAR as contributing significant recharge to urban and rural communities where groundwater serves as a significant source of supply. This consideration is not explicitly stated in Table 4-1 because the location of identified high vulnerability areas (HVAs) relative to public groundwater supply wells was included in the KRWCA HVA prioritization framework. Therefore, including recharge to community groundwater as an independent consideration, with it also incorporated into the vulnerability prioritization, would be redundant. Instead, the weight that would have been applied to it is reflected in a heavier weight for



vulnerability prioritization. A summary of how areas contributing recharge to public water supply were included in the HVA prioritization framework follows.

Public water system groundwater supply wells were identified using State Water Resources Control Board Division of Drinking Water (SWRCB-DDW) (formerly California Department of Public Health) source data obtained from the SWRCB Groundwater Ambient Monitoring and Assessment (GAMA) online database (SWRCB, 2014). Figure 16 presents the public water system groundwater supply wells identified in the KRWCA area. A total of 472 public groundwater supply wells were identified in the analysis.

Public groundwater supply wells within disadvantaged communities (DACs) were also incorporated in the KRWCA HVA prioritization framework. DACs are defined as places or communities whose median household income (MHI) is less than or equal to 80 percent of the statewide MHI. DAC boundaries in the KRWCA area are presented on Figure 17. All identified public water system groundwater supply wells presented on Figure 16 located within DAC boundaries were assumed to serve the respective DAC’s public water supply system. DAC wells are included on Figure 16 in yellow, along with non-DAC public water system groundwater supply wells. A total of 126 public groundwater supply wells associated with DACs were identified in the GAR.

Capture zones for all of the public groundwater supply wells discussed above were estimated using the uniform flow equations (Todd and Mays 2005). The uniform flow equations are a means of approximating the area of an aquifer that contributes flow to a well operating in a sloping groundwater surface. In these conditions, the contribution of flow to a well is not equal from all directions, but extends upgradient, with a stagnation point downgradient. The use of the uniform flow equations is recommended for the estimation of capture zones and identification of well head protection areas by the SWRCB-DDW Drinking Water Source Assessment and Protection (DWSAP) Program guidelines (CDPH, 1999).

The flow-lines ending in each well were buffered in GIS using the individually calculated capture zone distance estimated from the uniform flow equation. These capture zones were extended upgradient to a distance equivalent to 10 years of flow, estimated using the average linear velocity from the Darcy flow equation (Fetter 2000). The estimated 10-year capture zones for all of the public water supply wells, including the DAC wells, are shown on Figure 18.

Vulnerability Prioritization

The number of monitored wells determined for each township is also related to high vulnerability area prioritization tiers within the township, as determined by the GAR. To maintain a conservative estimate—err on the side of data collection—the highest priority HVA was considered in each township for scoring purposes. For example, if a township consists of low, medium, and high priority sections, it was considered a Tier I (high priority).

Scores range from zero to three. The three tier system determined in the GAR was used to score the HVA prioritization area. Areas of high priority are classified as Tier I and scored a three, areas of medium priority are classified as Tier II and scored a two, and areas of low priority are classified as Tier III and scored a one. If a township does not contain any HVAs it received a score of zero, but was not precluded from being selected as a trend monitoring location. It is important that the trend monitoring network be implemented over both high and low vulnerability areas.



The vulnerability prioritization identified in the GAR accounted for 65% (weight of 0.65) of the total consideration for number of wells selected. As indicated previously, the heavier weighting is a result of the HVA prioritization incorporating more parameters. In addition to recharge of community groundwater supply, the prioritization tiers are also a factor of hydrogeologic (intrinsic) sensitivity and the Nitrate Groundwater Pollution Hazard Index (NHI). A high vulnerability area prioritization map with overlaid proposed monitored well numbers is presented as Figure 19.

4.2.1.7 Groundwater Quality Records

The existence and duration of historic groundwater quality data is another factor in considering candidate trend monitoring wells. Such data provide a foundation with which to evaluate long-term trends in concentrations, especially as they relate to legacy conditions and changing agricultural practices. Primary consideration relating to the historic water quality results will be given during the well selection process. For the purposes of identifying potential candidate monitoring wells, the availability of historic nitrate and total dissolved solids (TDS) concentration data will be considered as these parameters are useful indicators of influences from irrigated agriculture, and because they are more widely available than many other water quality parameters. Consideration will also be given to availability of records for the other indicator parameters. While well records can provide a robust dataset, beneficial in trend analysis, a lack thereof is not substantial grounds for well disqualification. One of the reasons for choosing the long-term monitored wells in each township is to fill local data gaps. Thus, a well with no historical records may still prove beneficial in assessing regional groundwater quality.

4.2.2 Phase II – Specific Well Selection

4.2.2.1 Identify Candidate Wells

According to Attachment A to the General Order, “Existing shallow wells, such as domestic supply wells, will be used for the trend groundwater monitoring program” because using “existing wells is less costly than installing wells specifically designed for groundwater monitoring, while still yielding data which can be compared with historical and future data to evaluate long-term groundwater trends.” Therefore, only existing wells will be considered for inclusion in the GTMP well network.

An initial pool of candidate wells will be identified in Phase II of the GTMW. Wells will be located with the use of aerial photos, member growers’ farm evaluation data, DWR records, National Water Information System (NWIS) data, other agency data sources, and potentially by roadside surveys. Coalition member volunteered wells that meet criteria will also be considered.

4.2.2.2 Gather Additional Information

Once wells are identified, available information will be gathered from well owners, DWR records, and other sources in order to assess the wells for potential inclusion in the GTMP.

Well Details

Some well details are available in public databases, and should be confirmed by DWR Well Completion Reports with matching well log and construction details whenever possible, or through other reliable means, if necessary. Well construction details and other information for wells proposed for trend monitoring include:



• GPS coordinates;

• Physical address of the property on which the well is situated (if available);

• California State Well Number (if known);

• Well depth;

• Top and bottom perforation depths;

• A copy of the water well drillers log (if available);

• Depth of standing water (may be obtained after program implementation); and

• Well seal information (type of material and length).

Well Records

As discussed above, the existence of historical groundwater quality records is a factor in evaluating candidate trend monitoring wells. It is essential that all available well records are obtained from the appropriate sources and evaluated for duration and completeness. However, per Section 4.2.1.7, if well records are unavailable this may not be sufficient grounds for exclusion from the GTM network.

Well Accessibility

Candidate wells meeting the minimum criteria will be assessed for well owner agreement in order to be included in the well monitoring network. If agreement cannot be reached initially, discussions will continue with the well owner. Additionally, other suitable well owners within the same area will be contacted. Discussions with all well owners will continue until an appropriate well is selected and owner agreement is reached.

4.2.2.3 Site Survey/Verification

Candidate wells with access agreements will be visited by a qualified technician to conduct a field assessment of the well. Observations as to the accessibility of the well for sampling; general well surface condition; and proximity of the well to various influences such as animal enclosures, septic systems, or surface water features will be made. Additionally, the wells will be assessed for water treatment systems, and sampling and access ports.

Wells that are found to be unacceptable during the field assessment will be removed from future consideration for inclusion in the GTMP.

4.2.2.4 GTMP Network Established

Availability of required information, review of selection considerations, compliance of owners, and onsite verification will ultimately determine the wells to be included in the monitoring network. A summary discussion of the selected wells will be included in the second phase of the GTMW. Pertinent well information will be included in the second phase work plan, including all information listed in Section 4.2.2.2.

Due to the dynamic character of natural processes and human development and impact, and the long-term monitoring requirement, the well network will presumably need to be modified over time. Necessary changes will be made in order to maintain a regional representation of groundwater quality.

Section Five:

Implementation Groundwater Trend Monitoring Work Plan

Section Five: Implementation Groundwater Trend Monitoring Work Plan


5 Implementation 5.1 Coordination

Coordination with well owners and tenants will be conducted as necessary in order to provide notification of upcoming monitoring as well as necessary instructions.

5.2 Depth Measurements

To fully assess the potential regional effects of irrigated agricultural practices on groundwater, it is essential to capture the long-term groundwater elevation. This will be accomplished through routine measurement of the selected wells.

Prior to each sampling event for a monitored well, the static depth to water will be measured to calculate the elevation of the water surface. Generally, a weighted water level meter will be used to measure the depth to groundwater. All measurements will be recorded to the nearest 0.01 foot from a fixed and identifiable reference point at the top of the well. Each well’s reference point will be cataloged to ensure identical procedures are followed for subsequent measurements.

5.3 Quality Measurements

5.3.1 Schedule

As specified in the General Order, the GTMP network wells will be sampled annually at the same time of year. The KRWCA will sample in approximately June, after the spring rains and runoff, but prior to the peak pumping season. This will begin upon approval of the Phase II work plan.

Sampling the indicator parameters will occur according to Table 5-1 below. Annual samples will include conductivity, pH, dissolved oxygen, temperature, and nitrate as nitrogen. Total dissolved solids and the specified general minerals will be included in the initial sample and every fifth year thereafter.



Table 5-1. Groundwater Sampling Analyses and Schedule

All trend monitoring wells will be sampled for all minimally required constituents consistent with the General Order.

5.3.2 Procedures

5.3.2.1 Wellhead Survey

A wellhead survey will be performed by a licensed land surveyor registered in the State of California. A combination of Global Positioning System (GPS) and ground survey methods will be used based on the following datums:

• Horizontal – North American Datum of 1983 (NAD83), California Coordinate System of 1983 (CCS83) state plane coordinates.

• Vertical – North American Vertical Datum of 1988 (NAVD88)

Survey measurements will be reported to +/- 0.01 feet. The survey information will be tabulated and used for hydrograph preparation.

5.3.2.2 Purging Wells

In order to obtain a representative sample of the groundwater contained within the saturated zone, stagnant water within the well casing and filter material must be removed, and fresh formation water

Groundwater Sampling Analyses

Frequency Indicator Parameter Reporting Units

Field Measurement

Laboratory Analysis

Analysis Method

Initi

al S

ampl

e

5-Y

ear

Ann

ual

Electrical Conductivity (EC) µmhos/cm ● Field Instrument

pH pH units ● Field Instrument

Dissolved Oxygen (DO) mg/L ● Field Instrument

Temperature oC ● Field Instrument

Nitrate as Nitrogen mg/L ● Method 300.0

Total Dissolved Solids (TDS) mg/L ● Method 2540C

General Minerals - Anions (carbonate, bicarbonate, chloride, sulfate)

mg/L ● Method 2320B

General Minerals - Cations (boron, calcium, sodium, magnesium, potassium)

mg/L ● Method 200.7



must replace it. Removal of the stagnant water is accomplished by pumping or bailing the water contained within the well. Purged water will be dispersed on site.

Field parameters (pH, temperature, EC, and DO) will be monitored and recorded during the purge operations. Stabilization of pH, temperature, and EC parameters will be indicated by values within 10% of one another for a minimum of three consecutive readings. Field parameters will be measured using a pH meter calibrated to standard buffers, and an EC meter equipped with a thermometer. Field equipment will be standardized at the beginning of each use, according to the manufacturers' specifications and consistent with the Environmental Protection Agency Test Methods SW-846 Manual.

The methodology and procedures used to collect groundwater samples from groundwater wells included in the GTMP may vary depending on the type of each well. Industry standard protocols typically differ for domestic wells, groundwater monitoring wells (i.e., wells installed for the sole purpose of monitoring groundwater), and agricultural production wells. It is anticipated that the wells that will make up the trend monitoring network will be comprised chiefly of domestic wells.

Domestic Wells

Prior to purging and sampling, the condition of the well casing and water supply line(s) will be observed and documented. Collecting samples from a domestic well requires minimal equipment as the groundwater supply system typically includes a pump and pressure tank that can provide a reliable sample stream.

Water bibs closest to the wells and prior to any water treatment units will be used for purging and sampling in order to minimize the amount of piping the water will travel through, reduce purge times, and collect representative samples. As conditions allow, the same sample location at each well will be utilized during each sampling event. Prior to sampling, the wells will be purged by running the nearest available water bib or tap for up to 20 minutes or until a volume of water equal to the volume of the pressure tank has been removed. A hose may be used during purging activities to direct purge water away from the sampling point but will be removed prior to collecting samples from the water bib. Groundwater samples will then be collected immediately after purging.

Groundwater Monitoring Wells

If groundwater monitoring wells without dedicated purging and sampling devices are used, the monitoring wells will be purged with one or more of the following temporary devices. The purging and sampling devices will be placed near the top of the screened interval to ensure that shallow groundwater is sampled.

• Positive gas-displacement, TeflonTM and/or stainless steel-housed TeflonTM bladder pump;

• TeflonTM or stainless steel bailer with bottom discharge unit;

• Stainless steel submersible pump with galvanized piping;

• Peristaltic pump;

• Centrifugal pump;

• Two-stage air-lift pump (TeflonTM or stainless steel); or

• Disposable polyethylene bailers with polypropylene check ball.



When purging a low-yield well (one that yields less than three casing volumes prior to being purged to dryness), the well will be purged to dryness twice. When the well recovers the third time, and when it contains a sufficient volume of water for the required analyses, samples will be collected. At no time will a well be purged to dryness if the rate of recharge is such that formation water will cascade down the sides of the casing, or if a purge rate of greater than one-quarter gallon per minute can be maintained.

Groundwater samples will be removed from a monitoring well of moderate- to high-yield only after a minimum of three casing volumes have been purged from the well casing, and purging has been of sufficient duration to result in stabilization of pH, temperature, and EC measurements.

Agricultural Production Wells

If agricultural production wells are used, groundwater samples will be collected from the nearest available water supply valve or discharge opening prior to water treatment systems. Prior to sampling, the pump will be run for a minimum of 30 minutes or until at least three well volumes have been purged from the well.

5.3.2.3 Sample Collection

Samples of fresh formation water will be collected only after the appropriate volume of water has been purged from the casing, and field parameters have stabilized. To increase the likelihood that groundwater samples are representative of the groundwater contained within the formation, it is important to minimize physical or chemical alteration of the sample during the collection process.

Samples will be collected in such a manner as to minimize the volatilization of a sample due to agitation and/or transference from pump or bailer to sample container. The sampling flow rates will not exceed the purging process flow rate and will generally be much less. When a bailer is used to retrieve a sample, a bottom discharge unit will be used to minimize volatilization during transference between bailer and sample container.

5.3.2.4 Field Sampling Log

A field sampling log will be maintained for each sampling event and will include the following:

• Sampler's identification;

• Well identification;

• Climatic conditions;

• Depth to water prior to purging;

• Type of purging and sampling device;

• Purging rate and volume;

• Relative well yield volume;

• Field parameter measurements (pH, temperature, EC, DO);

• Type and number of samples collected; and

• Date and time collected.



5.3.2.5 Sample Handling

Sample Labeling

Sample containers will be labeled in the field. Labels will contain the following information:

• Consultant's identification;

• Project number or identification;

• Sampler's identification;

• Date and time of collection; and

• Sample identification.

Custody Seal

If it is necessary for samples or sample chests to leave the field technician’s control prior to delivery to the laboratory, such as for shipment by a common carrier, a custody seal will be placed on each sample container and/or sample chest to discourage tampering during transportation. The custody seal will contain the sampler's signature, and the date and time the seal was emplaced.

Chain of Custody

In order to document and trace sample possession, a positive signature chain-of-custody record will accompany the sample through the laboratory analyses. The completed chain-of-custody record will be included in the laboratory's final report.

Sample Analyses

Requests for sample analyses will be made in writing and will be included as part of the chain-of-custody record.

All samples will be delivered to the laboratory for analyses within the appropriate holding times. Sealed sample containers will not be opened by anyone other than the laboratory personnel who will perform the requested analyses.

Groundwater samples will be analyzed by a California Certified Environmental Laboratory Accreditation Program (ELAP) laboratory.

5.3.2.6 Quality Assurance and Quality Control

Field QA/QC

Travel and equipment blanks will be collected as appropriate and handled and transported in the same manner as the groundwater samples. Travel blanks prepared by the laboratory will be utilized at a rate of one per ice chest. Equipment blanks will be collected from non-dedicated sampling equipment at a rate of one per sampling episode by circulating steam-distilled water through cleaned sampling equipment during the final rinse stage.



Laboratory QA/QC

Duplicate samples may be collected at a total duplicate rate of 20 percent for the project. Blind duplicate samples will be delivered to the primary laboratory to verify the reliability of the laboratory's analyses.

Split samples may be collected at the discretion of the project manager. The split sample will be handled the same as the primary sample, but will be delivered to a second laboratory. A comparison of the split sample results will be made to further evaluate the primary laboratory's performance.

Duplicate and/or split samples collected from a single well will be collected from a single casing volume when possible. When a single casing volume is insufficient, samples will be collected in as rapid a succession as possible.

Quality assurance/quality control sample analytical data will be used to monitor the laboratory performance, sampling technique, and as indicators of potential sample analyses or sample collection anomalies.

For general minerals analysis, a cation/anion balance will be calculated by the laboratory as an error check using the commonly accepted standard of ±5%.

5.4 Equipment

5.4.1 Equipment Cleaning

When dedicated purging and sampling equipment is not used, equipment that may come in contact with the sample will be thoroughly cleaned prior to arrival to the project site. Non-disposable bailers and positive gas-displacement bladder pumps will be disassembled, steam-cleaned, rinsed with steam-distilled water, and then reassembled. Wires, hoses and connectors will be cleaned in a similar manner.

5.4.2 Equipment List

Depending on the type of well to be sampled, equipment from the below lists may be used during purging and sampling operations.

5.4.2.1 Decontamination Equipment

• 2x 5-gallon buckets

• Simple Green or other non-phosphate detergent

• Small head long handled scrub brush

• 1 ½” or 2” bottle brush

5.4.2.2 Purging Equipment

• Waterra Powerlift II actuator, Grundfos pump, or disposable bailers

• Horiba multimeter, or similar, with calibration solutions

• Solinst water level indicator or similar



• DO meter or other as needed

• Extra Waterra tubing, footer valves, and surge block if using the Waterra system

• 2x 5-gallon buckets

• Generator with gas

• Extension cord

• Tie-down strap or bungee

• Tool bucket (wrenches, pliers, all thread, zip ties)

• Latex gloves

5.4.2.3 Sampling Equipment

• Sample bottles

• Gallon self-sealing plastic bags

• Ice chest with ice

• Eye and ear protection

• Field camera

• Clipboard or forms box with the following:

• Client contact information

• Site map with well locations

• Field purge records

• Daily field records

• Waterproof fine point marker and ball point pens

• Sample labels

• Chain-of-custody forms

Section Six:

Data Packaging Groundwater Trend Monitoring Work Plan

Section Six: Data Packaging Groundwater Trend Monitoring Work Plan


6 Data Packaging 6.1 Reports

All groundwater data, to include applicable historical records, well details, elevation, and sampling results will be organized and maintained by the KRWCA. This information will be reported through multiple channels outlined below. Various methods of trend analysis, also detailed below, will accompany the raw data to show changes in groundwater attributes over time.

6.1.1 Annual Monitoring Report

Data obtained through the Groundwater Trend Monitoring Program will be synthesized and reported to the Central Valley Regional Water Quality Control Board by May 1 each year. The Annual Monitoring Report will include the monitoring period from the previous hydrologic water year (Oct 1 – Sept 30). It must include a map of the sampled wells, tabulation of the analytical data, and time concentration charts. Section V.C of Attachment B to the General Order contains a full list of the required report components.

6.1.2 Electronic Submission

In addition to the Annual Monitoring Report, the raw data are also required to be electronically submitted annually. Per Attachment B to the General Order,

“…the third-party shall submit the prior year’s groundwater monitoring results as an Excel workbook containing an export of all data records uploaded and/or entered into the State Water Board GeoTracker database. If any data are missing from the report, the submittal must include a description of what data are missing and when they will be submitted to the Central Valley Water Board. If data are not loaded into the GeoTracker database, this shall also be noted with the submittal.”

6.1.3 Other General Order Product Updates

There is significant interconnectivity among the products required by the General Order. Thus, the GTMP acts as a feedback mechanism. As a result, it is necessary to incorporate data results and analyses into the regular updates of related reports and programs.

6.1.3.1 Groundwater Quality Assessment Report

The Groundwater Quality Assessment Report is the foundational document for the other plans and programs required by the General Order. A key output of the GAR is the list of High Vulnerability Areas, which is subject to change over time. Thus, it must include an assessment of all available and relevant data to date. The General Order requires a GAR update every five years, and it is essential that each update incorporates the most recent data obtained from the GTMP well network (e.g., current nitrate concentrations in groundwater). This includes the tabulated and graphical arrangements, statistical trend analyses, and a discussion of the findings.



6.1.3.2 Comprehensive Groundwater Quality Management Plan

According to Attachment A to the General Order, “GQMPs are the key mechanism…to help ensure that waste discharges from irrigated lands are meeting Groundwater Receiving Water Limitation…” Rather than submitting separate management plans for noted water quality objective exceedances in groundwater, the KRWCA elected to submit a Comprehensive Groundwater Quality Management Plan (CGQMP). The CGQMP is designed with a monitoring strategy to provide feedback on progress. The long-term data trends recorded with the GTMP well network will be the primary input for revision of the CGQMP.

6.1.3.3 Management Practices Evaluation Program

The General Order explains that “the overall goal of the Management Practices Evaluation Program (MPEP) is to determine the effects, if any, irrigated agricultural practices have on first encountered groundwater…” The long-term data obtained as a result of the Groundwater Trend Monitoring Plan will be weighed against the implemented management practices cataloged in the MPEP to help determine if they are improving, or may result in improving, groundwater quality. The long-term trend analyses of the data are an important tool for accomplishing the goal of the MPEP.

6.2 Trend Analysis Methods

To fulfill General Order requirements, Annual Monitoring Reports (AMR) will include tabulated water level and water quality data (in Excel) and select trend analyses based on the suitability of the accumulated data set. These analyses may include the following:

• Maps - monitoring point locations, isoconcentration

• Graphs – groundwater elevation, time-series concentration

• Diagrams – Piper, Stiff

• Statistics

• Other analyses as appropriate - to be determined based on findings of the above

Collected data will be reviewed annually and the AMR will include a discussion of monitoring data relative to applicable water quality objectives and groundwater quality management plans. Generally, the more data points available, the more reliable the total set. Thus, the usefulness of the analysis methods should improve over time.

6.2.1 Maps

An initial monitoring point location map will be prepared once the GTMP network wells are established. The map will be updated with any well additions or removals from the GTMP.

Isoconcentration maps will be prepared annually for appropriate constituents of concern. A catalog of maps will develop over time and help to evaluate minimum and maximum concentration areas, as well as changes in those areas over time.



6.2.2 Graphs

Groundwater elevation graphs will be prepared from the initial monitoring event and updated annually. To be meaningful, these graphs rely on the change in elevation over time. It is anticipated that a minimum of five to ten years of data will be needed to begin to provide a representation of the changes in groundwater levels.

Time-series concentration graphs will be prepared from the initial sampling results and updated annually. As with the elevation graphs, these graphs rely on the change in constituent concentrations over time. A minimum of five to ten years of data will be needed to begin to assess the concentration changes.

Box and whisker plots may be used to help identify outliers on a constituent by constituent basis. A minimum of four sets would be needed.

6.2.3 Diagrams

Both Piper and Stiff diagrams require general mineral analyses that will be conducted for the initial monitoring event and every five years thereafter. Prior to diagram preparation, the monitoring data will be reviewed for internal consistency by comparing ionic balances of cations and anions using the commonly accepted standard of ±5%. The initial set of diagrams will be useful for determining water type spatial distribution in the region. Subsequent diagram sets will be compared every five years to assess changes over time.

6.2.4 Statistics

Statistical analysis methods will be used to assess the existence of groundwater quality trends (Table 6-1). These analyses are compromised by poor ionic balances, limiting the ability to draw conclusions. To minimize use of invalid datasets in statistical tests, each complete general mineral analytical suite result will be reviewed for internal consistency by comparing ionic balances, as noted above.

Statistical tests also require certain minimum datasets and most lose confidence with smaller datasets. Listed in the table below are potential statistical analyses that may be performed, and the sufficiency needs for each. Interpretation abilities will increase as the well data are collected in subsequent years. Initial statistical analysis will be limited and will likely include inter-well analysis. Appropriate statistical methods will be used depending on the presence and number of non-detects, and whether the data is parametric.



Table 6-1. Potential Statistical Tests

Potential Statistical Tests

Test Purpose Requirements

Dixon's Q Test Assess Outliers Minimum 3 Shewhart CUSUM Control Chart Detect dataset changes Minimum 2

Mann-Kendall Trend Minimum 4 Theil-Sen Trend slope calculations Minimum 8 ANOVA Inter-well analysis Minimum 4

Parametric and non-parametric analyses can be used depending on the dataset.

Section Seven:

Limitations Groundwater Trend Monitoring Work Plan

Section Seven: Limitations Groundwater Trend Monitoring Work Plan


7 Limitations The evaluations of groundwater conditions and water supply submitted in this work plan are based upon the data obtained from a review of generally available geologic literature for the subject areas. The validity of the opinions, findings, and recommendations presented in this work plan are based on the assumptions that the data reviewed and referenced are valid and correct.

As conditions within the region change due to natural processes, climate, or human intervention, or changes occur in the nature or design of the subject areas, or if there is a substantial lapse in time between the date of this work plan and the start of work in the subject area, the findings and opinions contained in our work plan will not be considered valid. Restoring validity will require that the changes are reviewed by Provost & Pritchard Consulting Group (Provost & Pritchard) and the findings and opinions contained in the work plan are modified or verified in writing.

Opinions, conclusions, and recommendations are made without a complete knowledge of the subsurface conditions. No assessment of site conditions can eliminate uncertainty or risk.

This work plan has been prepared in a manner consistent with the standards of care and skill ordinarily exercised by members of the profession practicing under similar conditions in the geographic vicinity and at the time the services will be performed. Regulations and professional standards applicable to Provost & Pritchard’s services are continually evolving. Techniques are, by necessity, often new and relatively untried. Different professionals may reasonably adopt different approaches to similar problems. Therefore, no warranty or guarantee, expressed or implied, is included in Provost & Pritchard’s scope of service.

Section Eight:

References Groundwater Trend Monitoring Work Plan

Section Eight: References Groundwater Trend Monitoring Work Plan

Kern River Kern River Watershed Coalition Authority • July 2017 8-1

8 References Boyle, D., King, A., Kourakos, G., Lockhart, K., Mayzelle, M., Fogg, G.E. & Harter, T. (2012) Groundwater Nitrate Occurrence. Technical Report 4 in: Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Center for Watershed Sciences, University of California, Davis.

Burt et al., (2014). Agricultural Expert Panel Recommendations to the State Water Resources Control Board pertaining to the Irrigated Lands Regulatory Program. In fulfillment of SBX2 1 of the California Legislature. September 9.

Canada, H.E., Harter T., Honeycutt, K., Jessoe, K., Jenkins, M.W. & Lund, J.R. (2012) Regulatory and Funding Options for Nitrate Groundwater Contamination. Technical Report 8 in Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Center for Watershed Sciences, University of California, Davis.

CDFA. (2013). Nitrogen Tracking and Reporting Task Force Final Report. California Department of Food and Agriculture. Sacramento, California.

CDPH. 1999. Drinking Water Source Assessment and Protection (DWSAP) Program, Sacramento, Cal.: Division of Drinking Water and Environmental Management, California Department of Health Services.

Chapman, D. and Kimstach, V. 1992. The Selection of Water Quality Variables. In Water Quality Assessments, 51-119. London, England: Chapman and Hall Ltd.

County of Kern. Agriculture and Measurement Standards. Bakersfield, Cal.: County of Kern. Available at http://www.kernag.com/gis/gis-data.asp. Accessed 12 September 2014.

Croft, M.G. 1972. Subsurface Geology of the Late Tertiary and Quaternary Water-Bearing Deposits of the Southern Part of the San Joaquin Valley, California. U.S. Geological Survey Water-Supply Paper 1999-H. Washington D.C.: United States Department of the Interior, Geological Survey.

CVRWQCB. 2012. Irrigated Lands Regulatory Program. Sacramento, Cal.: Central Valley Regional Water Quality Control Board. Available at: http://www.swrcb.ca.gov/rwqcb5/water_issues/irrigated_lands/index.shtml. Accessed 7 March 2014.

Dale R.H., J.J. French, G.V. Gorden. 1963. Ground-Water Geology and Hydrology of the Kern River Alluvial-Fan Area, California. USGS. Retrieved from: https://pubs.er.usgs.gov/publication/ofr6621. Accessed 27 March 2017.

DWR. 2016a. California’s Groundwater, DWR Bulletin 118, Interim Update 2016. Sacramento, Cal.: California Department of Water Resources.

DWR. 2016b. Land Use Survey. Sacramento, Cal.: California Department of Water Resources. Available at: http://www.water.ca.gov/landwateruse/lusrvymain.cfm. Accessed 17 March 2017.

http://www.kernag.com/gis/gis-data.asp

http://www.swrcb.ca.gov/rwqcb5/water_issues/irrigated_lands/index.shtml

https://pubs.er.usgs.gov/publication/ofr6621

http://www.water.ca.gov/landwateruse/lusrvymain.cfm



DWR- San Joaquin District. 1970. A Memorandum Report on Nitrates in Ground Waters of the San Joaquin Valley. Fresno, Cal.: California Department of Water Resources.

Dzurella, K.N., Medellin-Azuara, J., Jensen, V.B., King, A.M., De La Mora, N., Fryjoff-Hung, A., Rosenstock, T.S., Harter, T., Howitt, R., Hollander, A.D., Darby, J., Jessoe, K., Lund, J.R., & Pettygrove, G.S. (2012) Nitrogen Source Reduction to Protect Groundwater Quality. Technical Report 3 in: Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Center for Watershed Sciences, University of California, Davis.

Fetter, C.W. 2000. Applied Hydrogeology 4th ed. Harlow, Essex, England: Prentice Hall.

Gailey, Robert M, PG, CHG. 2013. Comments on Hydrogeologic Points of Concern for the Kern River Watershed Coalition Authority Area: Regarding Monitoring and Reporting Program Tentative order R5-2013-XXXX Waste Discharge Requirements General Order for Growers within the Tulare Lake Basin Area that are members of Third-Party Group. Pleasant Hill, Cal.: Central Valley Regional Water Quality Control Board. Available at: http://www.swrcb.ca.gov/centralvalley/water_issues/irrigated_lands/new_waste_discharge_requirements/tulare_lake_basin_area_wdrs/draft_tlb_wdr_mrp/revised_tlb_wdr/comments/ltr3_td4.pdf. Accessed 15 April 2014.

Harter, T. and J. R. Lund. (2012). Project and Technical Report Outline. Technical Report 1 in: Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Center for Watershed Sciences, University of California, Davis.

Harter, T., J.R. Lund, J. Darby, G. E. Fogg, R. Howitt, K.K. Jessoe, G. S. Pettygrove, J.F. Quinn, J.H. Viers, D.B. Boyle, H.E. Canada, N. DeLaMora, K.N. Dzurella, A. Fryjoff-Hung, A.D. Hollander, K.L. Honeycutt, M.W. Jenkins, V.B. Jensen, A.M. King, G. Kourakos, D. Liptzin, E.M. Lopez, M M. Mayzelle, A. McNally, J. Medellin-Azuara, and T.S. Rosenstock. 2012. Addressing Nitrate in California's Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Davis, Cal.: Center for Watershed Sciences, University of California, Davis. Available at: http://groundwaternitrate.ucdavis.edu. Accessed 8 September 2014.

Honeycutt, K., Canada, H.E., Jenkins, M.W. & Lund, J.R. (2012) Alternative Water Supply Options for Nitrate Contamination. Technical Report 7 in: Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Center for Watershed Sciences, University of California, Davis.

Hounslow, A. 1995. Water Quality Data: Analysis and Interpretation. Boca Raton, Fla.: CRC Press.

Jensen, V.B., Darby, J.L., Seidel, C. & Gorman, C. (2012) Drinking Water Treatment for Nitrate. Technical Report 6 in: Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater. Report for the State Water Resources Control Board Report to the Legislature. Center for Watershed Sciences, University of California, Davis.

http://www.swrcb.ca.gov/centralvalley/water_issues/irrigated_lands/new_waste_discharge_requirements/tulare_lake_basin_area_wdrs/draft_tlb_wdr_mrp/revised_tlb_wdr/comments/ltr3_td4.pdf

http://www.swrcb.ca.gov/centralvalley/water_issues/irrigated_lands/new_waste_discharge_requirements/tulare_lake_basin_area_wdrs/draft_tlb_wdr_mrp/revised_tlb_wdr/comments/ltr3_td4.pdf

http://groundwaternitrate.ucdavis.edu/



Jones, D.W., R.L. Snyder, S. Eching and H. Gomez-McPherson. 1999. California Irrigation Management Information System (CIMIS) Reference Evapotranspiration. Climate zone map, Sacramento, Cal.: Department of Water Resources.

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Figures Groundwater Trend Monitoring Work Plan


Kern River Watershed Coalition Authority • July 2017 F-1

Figure 1. Map of the Tulare Lake Basin Area



Figure 2. KRWCA Boundary Map



Figure 3. KRWCA Primary Boundary Generalized Soil Texture Map



Figure 4. Department of Water Resources Designated Groundwater Basins



Figure 5. 2007 Depth to Groundwater Contours



Figure 6. 2007 Depth to Shallow Groundwater Contours



Figure 7. 2007 Depth to Groundwater Contours



Figure 8. Illustrative Groundwater Elevation Hydrographs



Figure 9. Average Groundwater Elevation Contours (based on 2000 through 2013 Contours)



Figure 10. Horizontal Hydraulic Conductivity, Unsaturated Zone from CVHM



Figure 11. Vertical Hydraulic Conductivity, Unsaturated Zone from CVHM



Figure 12. 1990 DWR KRWCA Crop Map



Figure 13. 2013 KRWCA Crop Map



Figure 14. Historical DWR (1950-1969) and GAR Nitrate Exceedance Analysis Overlay



Figure 15. Crop Map and Proposed Monitoring Areas Overlay



Figure 16. Public Water System and Disadvantaged Community (DAC) Groundwater Supply Wells in KRWCA



Figure 17. KRWCA Disadvantaged Community Boundaries



Figure 18. Public Water Supply and Disadvantaged Community (DAC) Well Capture Zones



Figure 19. KRWCA High Vulnerability Area Prioritization Map and Proposed Monitoring Areas Overlay

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