Springflow Benefits for Pumping Forbearance East and West of Cibolo Creek

Edwards Aquifer Habitat Conservation Plan

Prepared for:Stakeholder Committees:

ASR and VISPO Work Groups

Prepared by:Larry Land, P.E. and Maureen Reilly, P.E. (CA) Sam Vaugh, P.E. and Phyllis Stanin, P.G.(CA)

July 31, 2014

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Topics of Discussion

Purpose and Scope Technical Approach and Assumptions Modeling Analyses Summary Conclusions

Purpose and Scope

PURPOSE: Establish the Springflow Benefits of ASR Leases

and VISPO Forbearance Agreements East and West of Cibolo

Creek

SCOPE: Test and Evaluate One Conceptual Scenario

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Technical Approach and Assumptions

Tasks

1. Estimate Availability of Potential Forbearance Agreements

for ASR Leases or VISPO East and West of Cibolo Creek

a) Selected 10,000 acft/yr of IRP for Test and Evaluation

East of Cibolo: 69% from Comal County and 31% from

Hays County

West of Cibolo: 60% from Medina County and 40%

from Uvalde County

NOTE: 10,000 acft/yr is 13.8 cfs

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Technical Approach and Assumptions(Continued)

Tasks (Continued)

2. Applications of Edwards Aquifer Model

a) Baseline Scenario

• Prepare a Baseline Pumping Dataset for 200,000

acft/yr. Distribution within County is a Prorated

Reduction of IRP. Monthly Distribution is Based on

Use Type

• Turn OFF Critical Period Management Controls

• Run the Model

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Technical Approach and Assumptions(Continued)

Tasks (Continued)

2. Applications of Edwards Aquifer Model (Continued)

b) East of Cibolo Creek Scenario

• Prepare a Pumping Data Set with a Forbearance of up

to 10,000 acft/yr

• Run the Model

c) West of Cibolo Creek Scenario

• Prepare a Pumping Data Set with a Forbearance of up

to 10,000 acft/yr

• Run the Model6

Technical Approach and Assumptions(Continued)

Tasks (Continued)

2. Applications of Edwards Aquifer Model (Continued)

d) Calculate Springflow Benefits to Comal and San Marcos

Springs

3. Deliverables, Meeting and Schedule

a) Powerpoint

b) Presentation to Work Groups

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Flowpaths and Forbearance (acft/yr)

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Source: EAA

4,000 6,000

6,900

3,100

West of Cibolo

East of Cibolo

Springs in MODFLOW

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Discharge from Springs

Notes: • Hueco Springs is not in model.• Barton Springs is lumped in with

Colorado River and simulated as a “River”.

• Las Moras Springs is considered to be insignificant for purposes of this study.

Groundwater Modeling Results

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Hydrographs at Springs and Index Wells Difference between Baseline Scenario and

East and West of Cibolo Scenarios Distribution of Springflow Benefits from

Forbearance Efficiency of Forbearance to Springs

J-17 and J-27

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Comal and San Marcos

Springs

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Forbearance Benefit

Comal and San Marcos

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5.6

3.9

0.4

8.8

Forbearance BenefitComal and San Marcos Combined

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12.7

6.0

Distribution of Forbearance Springflow BenefitScenario 1 (East of Cibolo)

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Leona San Antonio and San Pedro

Comal

San Marcos

Distribution of Forbearance Springflow BenefitScenario 2 (West of Cibolo)

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San Antonio and San Pedro

San Marcos

Comal

Leona

Summary of Forbearance Benefit to Springs

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Summary

Benefit to Minimum Springflow Comal Springs

• Eastern Forbearance (Scenario 1): +5 cfs• Western Forbearance (Scenario 2): +10 cfs

San Marcos Springs• Eastern Forbearance (Scenario 1): +10 cfs• Western Forbearance (Scenario 2): +0 cfs

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Summary

• Benefit to Long-Term Average Springflow• Comal Springs

• Eastern Forbearance (Scenario 1): +3.9 cfs• Western Forbearance (Scenario 2): +5.6 cfs

• San Marcos Springs• Eastern Forbearance (Scenario 1): +8.8 cfs• Western Forbearance (Scenario 2): +0.4 cfs

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Conclusions

• Forbearance in Comal and Hays Counties (Scenario 1)• About 28% of the Flow Benefit goes to Comal Springs, 64%

to San Marcos Springs, and 3% to Other Springs• About 5% goes to Storage (higher water levels), Los Moras

Springs and boundaries• Forbearance in Medina and Uvalde Counties : (Scenario 2)

• About 41% of the Flow Benefit goes to Comal Springs, 3% to San Marcos Springs, and 44% to Other Springs

• About 12% goes to Storage (higher water levels), Los Moras Springs and boundaries

• Results are Consistent with the Flowpath Map in Slide 15

Discussion

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Questions &Answers