Salt & Nutrient Management Plan Pajaro Valley Water Management Agency

Stakeholder Workshop #2March 28, 2013

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Agenda

• SNMP Overview (10 min)• Existing Groundwater Conditions (30 min)• Loading Analysis Approach – Nutrient loading risk analysis/findings (1 hr)– Salt loading risk analysis/findings (30 min)

• Assimilative Capacity Discussion (15 min)• SNMP Objective Development Discussion (30 min)• Stakeholder Next Steps (10 min)

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9 am – 1pm

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SNMP Development Process

Primary Tasks Schedule

Task 1. Stakeholder Outreach Stakeholder Meetings at critical milestones

Task 2. Conceptual Model Draft included

Task 3. Salt and Nutrient Loading Analysis Draft included

Task 4. Assimilative Capacity Estimate Draft Fall 2013

Task 5. Develop or update objectives Draft Fall 2013

Task 6. Develop or update priority program/projects Draft Fall 2013

Task 7. SNMP Monitoring Plan Draft Spring 2014

Task 8. Conduct anti degradation analysis Draft Spring 2014

Task 9. Complete SNMP Summer 2014

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Stakeholder Feedback Process

• Plan developed in iterative sections• Drafts vetted with stakeholders• Go to PVWMA website for report and

Stakeholder comment formhttp://www.pvwma.dst.ca.us/board-and-committees/salt-nutrient.php

• Comments must be submitted in writing, compiled on comment site

• Comments due by 04/12/2013• Responses tracked and available to all

Existing PVGB Groundwater Conditions

Approach• Analyze existing groundwater data

• 295 PVWMA Production & Dedicated Monitoring Wells• 14 City of Watsonville Production Wells

• Calculate statistics by site and constituent for the 10-year period: 2002-2011

• Map statistical results and then interpolate the decadal average and maximum concentrations using Inverse Distance Weighted method

• To protect the confidentiality of the well owner, results are maps that show interpolated concentration contours, but do not display individual well data

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Inverse Distance Weighted Method

• Predicts values at unmeasured locations based on measured values surrounding the prediction location.

• Local influence from measured data diminishes with distance.

• Method is being used to develop SNMPs elsewhere in the state.

Metered & Unmetered

Wells

[TDS] Range (mg/L) acres (%)0-450 35,300 (52%)

>450– 1000 27,900 (41%)>1000– 1800 3,550 (5%)

>1800 637 (1%)

GroundwaterAverage TDS

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[TDS] Range (mg/L) acres (%)0-450 29,300 (43%)

>450– 1000 30,500 (45%)>1000– 1800 6,950 (10%)

>1800 900 (1%)

GroundwaterMaximum TDS

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[Cl] Range (mg/L) acres (%)0-100 55,500 (82%)

>100– 250 8870 (13%)>250– 500 2600 (4%)

>500 644 (1%)

GroundwaterAverage Cl

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[Cl] Range (mg/L) acres (%)0-100 52,900 (78%)

>100– 250 10,400 (15%)>250– 500 3170 (5%)

>500 1200 (2%)

GroundwaterMaximum Cl

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[NO3] Range (mg/L) acres (%)0-10 25,500 (38%)

>10– 45 28,400 (42%)>45– 100 10,500 (16%)

>100 3,260 (5%)

GroundwaterAverage NO3

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[NO3] Range (mg/L) acres (%)0-10 24,600 (36%)

>10– 45 23,100 (34%)>45– 100 12,600 (19%)

>100 7,410 (11%)

GroundwaterMaximum NO3

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PVGB Groundwater Condition Summary

PVGB Area mapped: 67,500 acres

Constituent ThresholdFraction acreage above threshold

AVERAGE (%)

Fraction acreage above threshold

MAX (%)

TDS 1000 mg/L 6% 11%Chloride 100 mg/L 18% 22%

Nitrate-NO3 45 mg/L 21% 30%

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SNMP Pollutant Loading Analysis

RISK ANALYSIS APPROACH• Relative risk for each primary source • Identify primary factors driving potential loading• Identify available data to inform factor

contribution• Categorize relative contribution of sources based

on factors in risk matrices• Generate spatially explicit distribution of relative

risk within PVGB area.

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SNMP Pollutant Loading Analysis

ADVANTAGES• Relative risk for each primary source • Sensitive to same inputs as complex models, but

less debate on accuracy.• Transparent and easy to communicate• Focus confidence on relative risk designations • Informs priority locations/practices where

improvements would be most beneficial

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Soil [NH4+, NO3

-]

Atmosphere [N2(g)]

Groundwater [NO3-]

Relevant components of the NITROGEN CYCLE

Plants [N organic]

mineralizationuptake

Air Pollution [N2O]

Septic/sewer systems[NH4

+, NO3-]

deposition

applications leaks

Animal waste[NH4

+, NO3-]

fixation

leaching

Fertilizer[NH4

+, NO3-]

deni

trifi

catio

n

mineralization

Controllable sources

Key reservoirs

KEY

process

Upgradient sources

Downgradient migration

Irrigation water[NH4

+, NO3-]

Stormwater[NH4

+, NO3-]

runoff

Nitrogen – NO3 Risk Analysis

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Agricultural Fertilizer NO3 Loading Risk Analysis

Factors evaluated• Soil water holding capacity• Land use patterns• Annual irrigation volumes • Amount of N applied as fertilizer

Data sources used• NRCS Soil survey• PVWMA Ag crop land use data (2012 and 2011)• PVWMA and MCWRA water usage data and grower

surveys• NASS survey data and published literature values

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Agricultural Fertilizer NO3 Loading Risk Analysis

Soil water holding capacity• NRCS data used for 1-100 cm soil depth• 4 categories based on amount of water held by soil, soil

texture data and slope• Categories are specific to the diversity of soil conditions

within the Pajaro Valley

Categories• Low – capacity to hold up to 0.75 AF per acre• Moderate – capacity to hold 0.75 – 1.25 AF per acre• High – capacity to hold 1.25 – 1.5 AF per acre• Very High – capacity to hold 1.5 – 2.3 AF per acre

Relative Soil Water Holding Capacity

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Agricultural Fertilizer NO3 Loading Risk Analysis

Land use patterns• PVWMA Ag land use data averaged for 2011 – 2012• 6 categories based on crop groups specific to agricultural land

use within the Pajaro Valley

Categories• Vegetable row crops including artichokes, broccoli, cabbage,

cauliflower, celery, lettuce, spinach and other leafy greens• Horticulture nurseries including bulb production facilities, cut flower

operations, landscape plants and transplant operations• Strawberries• Caneberries• Deciduous trees – orchards• Other agriculture production including vines, grapes and

miscellaneous crops

Land Use Category Acres %Vegetable Row Crops 9,138 13

Horticulture Nurseries 1,343 2Strawberries 7,994 11Caneberries 5,003 7

Deciduous (Orchards) 2,179 3Other, Unknown Ag, Vines/Grapes 1,142 2

Non-agriculture land uses 43,158 62Total 69,957 100

PVGB Ag Land Use

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Agricultural Fertilizer NO3 Loading Risk Analysis

Irrigation intensity• PVWMA usage data, MCWRA usage data, and published

literature data sources• 3 categories based on range of values by crop group• Categories are specific to the irrigation requirements based

on both crop and cool climate within the Pajaro Valley• Individual agriculture operations may have usage patterns

different than values used for each crop groupCategories

• Low – usage of 0.5 – 1.7 AF per acre, such as grapes and orchards• Moderate – usage of 1.8 – 2.3 AF per acre, such as strawberries,

caneberries and other acreage on drip irrigation• High – usage of 2.4 – 3.0 + AF per acre, such as double cropped

vegetable row crops and other acreage utilizing sprinkler irrigation

Irrigation category % of Ag landHigh 39

Moderate 49

Low 12

Agricultural land 26,799 acres

Non-agricultural land 43,158 acres

Irrigation Intensity

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Agricultural Fertilizer NO3 Loading Risk Analysis

Agriculture crop fertilizer use • NASS surveys, PVWMA surveys, and published literature data

sources• 4 categories based on a range of values by crop group• Categories are specific to the diversity of crops and the soil fertility

conditions within the Pajaro Valley• Individual agriculture operations may have usage patterns different

than values used for each crop group

Categories• Low – usage of 35 – 75 lbs. N per acre, such as grapes, certain horticultural

operations and miscellaneous crops• Moderate – usage of 76 – 149 lbs. N per acre, such as orchards, caneberries• High – usage of 150 – 250 lbs. N per acre, such as strawberries , vegetable row

crops and certain horticultural operations• Very High – usage of over 250 lbs. N per acre, as may occur under certain

conditions of crop production

Fertilizer category Meas.% ag land

Expect%

Very High 29

High 69 40

Moderate 27 27

Low 4 4

Ag land 26,799 acres

Non-ag land 43,158 acres

Fertilizer Intensity

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Agricultural N Risk Matrix

Irrigation Intensity Fertilizer Intensity Soil Water Holding Capacity

Based on crop type

Agricultural Fertilizer NO3 Loading Risk Analysis

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Agricultural N Risk Matrix

Water Holding Capacity (AF) Water

(AF/acre/year) Fertilizer

(lbs. N/acre/year) Very High (1.5 - 2.3)

High (1.25 - 1.5)

Mod (0.75 - 1.25)

Low (< 0.75)

High (2.4 - 3.0+)

High (150 – 250+) MOD RISK HIGH RISK HIGH RISK HIGH RISK

Mod (1.8 - 2.3)

High (150 – 250+) MOD RISK MOD RISK HIGH RISK HIGH RISK

Mod (1.8 - 2.3)

Mod (76 - 149) LOW RISK MOD RISK MOD RISK HIGH RISK

Low (0.5 - 1.7)

Mod (76 - 149) LOW RISK LOW RISK MOD RISK MOD RISK

Low (0.5 - 1.7)

Low (35 - 75) LOW RISK LOW RISK LOW RISK LOW RISK

Agricultural Fertilizer NO3 Loading Risk Analysis

Ag nitrate loading risk Acres % of Ag Land

HIGH 14,312 53%MODERATE 10,224 38%

LOW 2,263 8%Total Ag land 26,799 100

AgricultureN Risk

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Septic N Risk Analysis

Factors : presence and soil typeSeptic GIS data Monterey and SC CoMonterey Co data generated using CAD plans by 2N. 4500 of septic systems in PVWMADensity exceeds 400 units/sq mi in some locations

Septic nitrate loading riskNumber of

septic systemsSC/Mo %

HIGH 1889 1023 / 866 42

MODERATE 2152 1955 / 197 48

LOW 431 311 / 120 10

Total 4472 100

Septic N Risk Analysis

Septic risk # SCC /MoC %

HIGH 1023 / 866 42%

MODERATE 1955 / 197 48%LOW 311 / 120 10%Total 4472 100%

SepticN Risk

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Sewer N Risk Analysis

Factors : presence and soil typeSewer GIS data Monterey and SC CoMonterey Co data generated using CAD plans by 2N. 146 miles of sewer lines in PVWMA

Sewer riskTotal

Length (miles)

%

HIGH 19.4 13%

MODERATE 72.7 50%

LOW 53.7 37%Total 145.8 100%

SewerN Risk

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Surface water infiltration N Risk Analysis

Q3 nitrate-NO3 MEAN concentration (Figure 4.7) Stream bed

vertical Very Low Low Mod High

conductivity < 10 mg/L 10 > 45 mg/L 100> 45 mg/L > 100 mg/L Very High LOW RISK MOD RISK HIGH RISK HIGH RISK (>3.0 m/day)

High LOW RISK MOD RISK HIGH RISK HIGH RISK (1.0-3.0 m/day) Mod LOW RISK MOD RISK MOD RISK MOD RISK (0.25-1.0 m/day) Low LOW RISK LOW RISK LOW RISK LOW RISK (0.01-0.25 m/day)

Very Low (<0.01 m/day) LOW RISK LOW RISK LOW RISK LOW RISK

Factors : stream bed conductivity and mean Q3 [NO3]

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StreamflowInfiltration

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Surface water infiltration N Risk Analysis

StreamflowN Risk

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• Agricultural Irrigation o Potential opportunity to manage fertilizer appso Similar outcome as fertilizer risk

• Riparian land use risko Buffer approach

• Urban storm water runoffo Localizedo Low recharge in Sloughs

• Atmospheric o Uncontrollable

• Animal Wasteo Minimal presence

Subordinate Sources N loading

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N loading ACROSS sources

N Source Average annual N load to groundwater (t/yr)

Agricultural land use 1,742

Septic systems 67

Sewer systems 66

WWTP 80

Streamflow infiltration 746

Total PVGB 2,700 t/yr

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Agriculture: 1742 t N/yr

Mass of N leaching to gw per year per acre * acres of Ag in PVGB

130 lbs N/acre/yr x 26,799 acres of ag

• 134 lbs N/acre/yr (Viers et al 2012; study area average)• 123 lbs N/acre/yr (Viers et al 2012; Mo Co area average)

N loading ACROSS sources

Tulare/Salinas Basins (Viers et al 2012)

PVGB

High fertilizer demand crop distribution (% of ag land)

40 % 67%

Ave fertilizer application rate(lbs N/acre of ag land /yr)

145 180

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SEWER (67 t N/ yr)• Fraction of N per person lost (1-25%)

25% of 55,000 people waste

SEPTIC (66 t N/yr)• Fraction of N per person lost (85%)

16,100 people on septic

WWTP (80 t N/yr)• 6.6 million GPD treated, 50% infiltrated @ 16 mg/L NO3

Stream flow recharge (746 t N/yr)• USGS annual recharge (AF/yr) * NO3 SW conc.

18,300 AF/yr * 30 mg/L

N loading ACROSS sources

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Sources in PVGB• Seawater Intrusion• Irrigation practices• Surface water recharge

Salt loading risk analysis

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• Seawater IntrusionSeawater Intrusion

Risk

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Plant Growth

SALT leaching

Evapotranspiration

Soil SALT adsorption

SALT leaching

Evapotranspiration

Soil SALT adsorption

Plant Growth

Aquifer SALT

Aquifer SALT

Irrigation volumes

SALT CYCLING ON IRRIGATED LAND

HIGH

HIGH

Low

Low

HIGH

HIGH

HIGH

HIGH L

Salt content of irrigation waterHIGH Low

Low

Low

Low

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Factors• Annual water use• Irrigation water TDS content• Soil water holding capacity

Irrigation salt loading risk

Water Holding Capacity (AF)

Water USE Irrigation Water TDS Very High High Mod Low

(AF/acre/year) (mg/L) (>1.5) (1.25 - 1.5) (0.75 - 1.25) (< 0.75)

All categories High MOD RISK HIGH RISK HIGH RISK HIGH RISK (>1000) High Mod MOD RISK MOD RISK HIGH RISK HIGH RISK (2.4 - 3.0+) (450-1000) Mod Mod LOW RISK MOD RISK MOD RISK HIGH RISK (1.8 - 2.3) (450-1000) Low Mod LOW RISK LOW RISK MOD RISK MOD RISK (0.5 - 1.7) (450-1000)

All categories Low LOW RISK LOW RISK LOW RISK LOW RISK (<450)

Irrigation salt risk Acres %

HIGH 6,647 25

MODERATE 9,669 36LOW 10,285 39

Total Ag land 26,601 100

IrrigationSalt Risk

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Surface water infiltration SALT Risk Analysis

Factors : stream bed conductivity and mean Q3 [TDS]

Q3 TDS MEAN concentration (Figure 4.10) Stream bed vertical Very Low Low Mod High

conductivity < 450 mg/L 1000 > 450 mg/L 1800 > 1000 mg/L > 1800 mg/L Very High LOW RISK MOD RISK HIGH RISK HIGH RISK (>3.0 m/day)

High LOW RISK MOD RISK HIGH RISK HIGH RISK (1.0-3.0 m/day) Mod LOW RISK MOD RISK MOD RISK MOD RISK (0.25-1.0 m/day) Low LOW RISK LOW RISK LOW RISK LOW RISK (0.01-0.25 m/day)

Very Low (<0.01 m/day) LOW RISK LOW RISK LOW RISK LOW RISK

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StreamflowSalt Risk

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Assimilative Capacity Discussion

• Required Task of SNMP• Intent of task is to identify areas of concern and areas

where standards are met• No specific GW standards for PVGB

• Clarification from Regional Board requested

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SNMP Objective Development

Useful strategy implementation objectives are:• Future vision statements and time frame• Measurable• Used to communicate and track progress toward future

vision• Used to guide strategy/project development and

prioritization• Used to guide monitoring needs, purpose and use of data

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Pajaro River Watershed IRWM WQ Goal and ObjectivesWater Quality Goal: Protect and improve water quality for beneficial uses consistent with regional community interests and the RWQCB basin plan objectives through planning and implementation in cooperation with local and state agencies and regional stakeholders.

Water Quality Objectives:1. Meet or exceed all applicable groundwater, surface water, wastewater, and

recycled water quality regulatory standards.2. Identify and address the drinking water quality of disadvantaged communities

in the Pajaro River Watershed.3. Protect groundwater resources from contamination including salts and

nutrients.4. Address impacts from surface water runoff through implementation of Best

Management Practices or other surface water management strategies.5. Meet or exceed delivered water quality targets established by recycled water

users.

SNMP Objective Development

Actions

Join a gym Physical Health

Weight (lbs)

Diet, ExerciseGenetics

Jog (mi/wk)

Increase sewer

Groundwater Quality

NO3 distr [mg/L]

Septic LeakageLegacy pollution

Septic density (# area)

Alternative Objectives

Protect groundwater resources from contamination including salts and nutrients.

Reduce the distribution of maximum groundwater NO3 concentrations to < 15% of total PVGB area by 2034.

Reduce septic density to 40/sq mi in Freedom and Corralitos by 2034.

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Increase sewer

Groundwater Quality

NO3 dist [mg/L]

Septic LeakageLegacy pollution

Septic density (#/area)

Protect groundwater resources from contamination including salts and nutrients.

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Challenges with measurable objectives

• Difficulty and reluctance to prioritize if results in missed opportunities

• Political or regulatory implications if targets are not achieved.

• Broader community vision but PVWMA lacks authority to require priority strategies to be implemented.

• Others?

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Stakeholder Objectives Feedback

Desired approach

Concerns or desires

Potential areas of objective development focus by team

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Next Steps for Stakeholders1. Download Draft Ch1.-5 of SNMPhttp://www.pvwma.dst.ca.us/board-and-committees/salt-nutrient.php

2. Submit comments on google docs form by APRIL 12.

3. Comments in writing, specific recommendations of changes required.

4. Team will respond on Google Doc by April 30 and alert Stakeholders

5. Next stakeholder meeting and draft sections in late summer/early fall

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SNMP Development Process

Primary Tasks Schedule

Task 1. Stakeholder Outreach Stakeholder Meetings at critical milestones

Task 2. Conceptual Model Draft included

Task 3. Salt and Nutrient Loading Analysis Draft included

Task 4. Assimilative Capacity Estimate Draft Fall 2013

Task 5. Develop or update objectives Draft Fall 2013

Task 6. Develop or update priority program/projects Draft Fall 2013

Task 7. SNMP Monitoring Plan Draft Spring 2014

Task 8. Conduct anti degradation analysis Draft Spring 2014

Task 9. Complete SNMP Summer 2014