RiverWare User’s Group Meeting
Pecos River Adjudication Settlement: Application of an
Integrated Surface and Ground Water Modeling System
June 18, 2003
Presentation Outline
• Overview of Pecos River Institutions / Operational Policies
• Adjudication Settlement: Problems and Solutions
• The Pecos River DSS• Evaluating the Settlement Terms• Conclusions
Institutions and Operations
• Pecos River Compact and Amended Decree (New Mexico / Texas)
• Water Rights - Prior Appropriation Doctrine; adjudication and administration
• ESA operations for Pecos Bluntnose Shiner• 2 NEPA EIS programs• Carlsbad Project (reservoir operations, GW
diversions)• Other diverters (FSID, river pumpers, M&I, etc)• PVACD groundwater diversions
Major Irrigators, Physical Features, and Critical Resource Locations in the Pecos Basin
Carlsbad Irrigation
District
Fort Sumner Irrigation District
Santa Rosa Reservoir
Brantley Reservoir
NM - TX State Line / Pecos River Compact
Pecos Valley Artesian Conservancy District
USGS gage PR @ Acme
Sumner Reservoir
Pecos Adjudication Settlement
• Parties: PVACD, CID, NM ISC, United States
• Purpose:– Ensure long-term compliance with the Pecos River
Compact and Amended Decree– Avoid need for priority administration of water rights– Maintain or enhance water supplies / aquifer storage
levels• Proposal:
– NM ISC purchases water rights / land from PVACD and CID
– CID water delivered to state line for Compact deliveries– PVACD lands retired, water provides augmentation
supply when needed
Pecos Adjudication Settlement - Evaluation of
the Proposal• Use existing modeling tools to evaluate and
refine Settlement terms.• Pecos River DSS integrates RiverWare, two
MODFLOW models, an accounting model, and numerous I/O tools.
• “Rules” simulate baseline conditions and proposed actions.
• Various resource indicators used to quantify “value” of actions by comparing baseline and Settlement model results.
Approximate Spatial Domain of Pecos Decision Support System Models
Pecos River RiverWare
Model
Roswell Artesian Basin Groundwater Model
Carlsbad Area Groundwater
Model
Red Bluff Accounting Model
Santa Rosa Reservoir
Brantley Reservoir
NM / TX State Line
Pecos River RiverWare Model• Rule-based
simulation of Pecos River hydrology and reservoir operations from Santa Rosa Reservoir to Avalon Dam
• USBR, Tetra Tech, Hydrosphere, Pecos HWG
Roswell Artesian Basin Groundwater Model
• Calibrated MODFLOW model of groundwater flow in Roswell Artesian Basin, in both the deep artesian and shallow alluvial aquifers
• Simulates areal and stream recharge, pumping stress, Pecos River - groundwater interaction
• Predicts base inflows to the Pecos River
• Amy Lewis, NM SEO (Eric Keyes), SSPA, Hydrosphere
Carlsbad Area Groundwater Model
• MODFLOW model that simulates groundwater flow in the Capitan Reef and overlying alluvial aquifer in the Pecos River Basin from Lake Avalon to the Malaga Bend
• Simulates surface-water irrigation, groundwater diversions, losses, and return flows
• Predicts base inflows to the Pecos River
• Amy Lewis, NM SEO (Peggy Barroll), Intera/Hydrosphere
Red Bluff Accounting Model• Computes Monthly and Annual Flows at
Red Bluff– Historical (Calibration)– Current Conditions (Alternative Evaluation)
• Red Bluff Flow = Resource Indicator– Evaluation of Policy Alternatives– Interstate Compact Implications
• Calculation of Calibration Targets for CAGW
Data Processing Tool (DPT)• Input/Output for
Models• Data Archiving/
Metadata• Alternative
Evaluation and ArchivingRiverWare
Data ProcessingTool RBAM
CAGWRABGW
Settlement Modeling Challenges
• CID Allotment based on surface water supply (RiverWare)
• Augmentation pumping in Roswell Basin conditioned on CID water supply: pumping occurs when CID supplies short of 90Kaf; up to 35Kaf/year, 100 Kaf per 5-year accounting period (Feedback from RiverWare to RABGW model)
• Compact credit thresholds computed by Red Bluff model drive RiverWare rules for water deliveries (Feedback from RBAM, via CAGW, to RiverWare):– Carlsbad Irrigation District allotment and distribution – Delivery of water to Texas
RiverWareRes Ops
Water DeliveryData Processing
Tool (DPT)
Red BluffAcct Model
Pecos Compact
CAGWSurface water diversions
Supplemental GW pumping
RABGWLand RetirementAug. Pumping
Pecos Decision Support System: Model Linkages
Feedback Loops: Compact deliveries drive reservoir ops CID Supply drives Roswell augmentation pumping
Settlement Model Implementation
• Baseline model w/ Settlement Rules• Iterate between RiverWare and RABGW to
determine total augmentation pumping• Sensitivity analysis in Carlsbad GW model;
results used by RiverWare to estimate compact credit
• Simulate basin operations to state line and verify estimates used in RiverWare
Evaluation of Settlement Terms
• Avoid priority administration (50,000 AF Supply on March 1)
• Meet Compact delivery requirements (Stateline flows and Compact accounting)
• Maintain or enhance CID water supply• Maintain or enhance Roswell basin aquifer
storage levels
Resource Indicator: Roswell Basin Aquifer Storage
Derived from RABGW ModelLayer 1 RABGW Model, Alluvial Aquifer
Predevelopment Storage ~ 17.3 million afSimulation Start Date = Jan 1, 2000
-18.0%
-17.5%
-17.0%
-16.5%
-16.0%
-15.5%
-15.0%
-14.5%
-14.0%
-13.5%
-13.0%
-12.5%
-12.0%
1 4 7 10 13 16 19 22 25 28
Year
No
rmali
zed
Sto
rag
e D
efi
cit
(af)
Baseline
Settlement
Resource Indicator: CID Supply and Sources - March 1 Supply - Settlement
ScenarioCID Surface Water Supply - March 1
0
20000
40000
60000
80000
100000
120000
140000
1 4 7 10 13 16 19 22 25 28
Year
To
tal
Su
pp
ly D
eli
ve
rab
le a
t A
va
lon
(A
cre
-fe
et)
Augmentation from PVACD Wells
Pecos River Native Flow
Resource Indicator: Compact Obligations and Departures: Cumulative Departure
Cumulative Compact Departure from Obligation Initial Condition = January 1, 2000
-200
-150
-100
-50
0
50
100
150
200
250
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29
Year
To
tal
Dep
art
ure
(T
ho
usan
ds o
f A
cre
-Feet)
Baseline
Settlement
Average Departure = (-2,950 af/yr)
Average Departure = 6,430 af/yr)
Settlement Gains to Stateline Flows Sources of Additional Stateline Flow under Proposed Settlement
-30000
-20000
-10000
0
10000
20000
30000
1 4 7 10 13 16 19 22 25 28
Year
So
urc
e F
low
(A
cre
-fee
t)
0
50000
100000
150000
200000
250000
300000
ISC Release of CID Water Rights
Conservation Spills
Baseflow Gains from CID Return Flows
Cumulative Gain in Stateline Flow
What’s Next?
• Settlement parties signed agreement in spring 2003
• Ongoing applications of PRDSS:– Identification/evaluation of candidate lands
for retirement (PVACD and CID)– FWS B.O. on Pecos Bluntnose Shiner– Identification, evaluation, and refinement of
alternatives for ongoing Carlsbad Project EIS– Annual Carlsbad Project water accounting
(Reclamation)
Settlement Model Assumptions
(example)• Distribution of water from 6,000 acres of CID land purchased by
ISC conditioned on cumulative Compact credit and current water supply (ISC water “yield” = 1.176 x allotment):– If CID supply < 50Kaf on March 1, ISC water realloted to CID– If credit < 50Kaf, deliver ISC water to stateline 5x annually– if 50Kaf < credit < 115 Kaf, AND current supply > 90Kaf, ISC gets all
water > 90 Kaf, up to 24,696 af (3.5x1.176x6000). Beyond 114,696 af, water is alloted to all 25,055 acres equally.
– if 50Kaf < credit < 115 Kaf, AND current supply < 90Kaf, ISC shall make its CID water available for re-distribution to CID irrigators up to 3.5 af/acre (90Kaf)
– if credit > 115 Kaf, ISC shall make its CID water available for re-distribution to CID irrigators up to decreed limit (3.697 af/acre); IF CID irrigators have full allotment, excess water to be held over in storage
RiverWare Rulebased Simulation
• Operational policy is simulated using RiverWare rules
• Management alternatives can be readily evaluated
RiverWare - Implementation• USBR began work in 1991 following FWS B.O.
– Data collection program– Daily timestep model of river/reservoir operations– Need to evaluate operational alternatives
• HWG review / enhancement process started 1999– Evaluation of data and methods (side inflows,
routing, gain/loss, evaporation, bank storage, etc.)– Development of “Ruleset” representing current
reservoir operations policy
• Relevance to Settlement:– Impact of reservoir operations and physical
processes on Texas deliveries and CID allotments– Long-term water supply implications
Roswell Artesian Basin Groundwater Model -
Implementation• RABGW “roots”: Lewis model (1991-
1995); Keyes and SSPA enhancements• Calibrated based on 1967-2000 heads,
1967-2000 pumping data, and 67-2000 Pecos River base inflows
• Relevance to NEPA process:– Interrelationships between surface water
deliveries, well pumping, and climatic drivers– Direct impact on Pecos River flows from
Acme to Artesia
Carlsbad Area Groundwater Model - Implementation
• CAGW “roots”: Lewis model (1991); Bjorklund and Motts survey (1959)
• Updated and enhanced by NM OSE and Intera
• Relevance to Settlement:– Interrelationships between surface water
deliveries, supplemental well pumping, and return flows
– Direct impact on Pecos River flows below Avalon (and thus stateline deliveries)
RBAM - Implementation
• Mass-balance calculation of Red Bluff flows – Input includes RiverWare and CAGW outputs
via DPT
• Monthly and annual surface-water budget for the Avalon to state-line reach
• Relevance to Settlement:– Pecos Compact obligations and departures– Impacts of potential changes in reservoir
operation and CID irrigation supply sources on stateline deliveries
DPT - Implementation
• Coupling of RiverWare, CAGW, and RBAM• RiverWare post-processing
– CID diversion, Avalon seepage and Avalon releases– Time-step conversion
• CAGW pre- and post-processing– Determination of CID supplemental well pumping
entitlements– Computation of Pecos River gains below Avalon
• Archiving– Data– Policy alternatives
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