An Interregional Water Solution with Conjunctive Use of Groundwater Haskell L. Simon President,...

An Interregional Water Solution with

Conjunctive Use of Groundwater

Haskell L. SimonPresident, Coastal Plains Groundwater Conservation District

Vice President, Region K Water Planning Group

New Era for Water Planning Based on “Bottom Up” or “Grass Roots” Approach

Address anticipated water shortages over a 50 year period by determining: Available water supplies Demands for water Strategies to achieve projected short falls

SB1 (1997)Mandate for Statewide Water Plan

The Essence of the SB1 Process

Top Down Approach vs. Bottom Up Approach

Before Today

16 Regions in Texas Each group represented by one or more individuals

from 11 “Interest Groups”

RWPG is responsible for preparing and adopting a regional water planRegional Plans consolidated into the State Water Plan “Water for Texas 2002”Implementation of the Plan will require legislative and/or regulatory action.

SB1 Regional Approach

Regional Water Planning Areas

Regional Planning Group Membership(11 Interest Groups)

1. Public

2. Counties

3. Municipalities

4. Agricultural Interests

5. Environmental Interests

6. Industries

7. Small businesses

8. River Authorities

9. Water Districts

10. Water Utilities

11. Electrical Generating Utilities

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2

4

6

8

10

12

1990 2000 2020 2030 2040 2050

Agricultural

Urban

Year

Mil

lio

n A

cre

-fe

et

Projected Urban & Agricultural Water Uses

Total Water Demand by Type of Use (2003)

Irrigation63%

Steam Electric10%

Mining2%

Livestock1% Municipal

21%

Manufacturing3%

Steam Electric17%

Mining2%

Livestock1%

Municipal37%

Irrigation36%

Manufacturing7%

Year 2000 Year 2060

Use by Source of Supply (2000)

SURFACE WATER

65%

GROUND-WATER

35%

2050 Water Needs

SB 1 Planning Process(entire state & border regions)

Region K2050 Shortfalls • 160,000 acre-feet/yr of irrigation • Some rural communities upstream of Highland Lakes (5,400 acre-feet/yr)

2050 Water Needs

SB 1 Planning Process(entire state & border regions)

Region L

Bexar County shortfall• 350,000 acre-feet/yr of municipal use(current update to plan will reduce this amount)

Regional Cooperation Defines Project

SB 1 Planning Process(entire state & border regions)

Region K(LCRA)

Region L(SAWS)

LCRA-SAWS Water

Project

Regional sharing of resources to meet future water needs

The LCRA-SAWS Water Project is designed to meet the needs of both the lower Colorado River basin and the San Antonio areaThe lower Colorado River basin needs additional water

to satisfy agricultural needs, protect Highland Lake levels and provide water for upstream rural communities

San Antonio needs significant additional water to meet growth and economic development needs

Project Summary

Construct off-channel reservoirs to store surface waters

Institute practices and improvements to reduce agriculture’s demand for water

Install groundwater wells to serve agriculture’s needs during drought

Create up to 150,000 acre-feet per year for SAWS

Meet environmental requirements

Study Period activities determine implementability and permitting

LCRA-SAWS Water Project

More stable water levelsin Highland Lakes

Water for agriculture

Water for ruralcommunities

Austin

San Antonio

LakeBuchanan

Freshwater inflows forMatagorda Bay

Instream flows to

maintain aquatic habitat

Water for San Antonio(up to 150,000 ac-ft/yr)

LCRA SAWS Water Project

Develop 330,000 ac-ft of water by:

1. Irrigation conservation-Onsite and system improvements in districts

P

P

3. Conjunctive use of groundwater for agricultural needs during drought

Matagorda Bay

Bay City

Wharton

Columbus

Colorado

Wharton

Matagorda

2. Off-channel reservoirs

Legislation requires that in order for the project to proceed, the project must ...

1. Protect and benefit basin interests2. Be consistent with the state regional water plan3. Provide inflows adequate to maintain the ecological

health and productivity of Matagorda Bay4. Maintain current instream river flow protections5. Ensure that San Antonio practices stringent conservation

measures6. Provide for a broad public and scientific review process7. Benefit stored water levels in Lakes Travis and Buchanan

We are at the beginning of a multi-year, comprehensive evaluation

2002 2007-2008 20102004

Technical Study Plan

DevelopmentTechnical Studies

Permit Submittal &

Continuation of Studies

Permitting Review &

Completion of Studies

Groundwater

Average of 62,000 ac-ft per year in severe droughts

Divert only to Colorado basin agricultural users

Groundwater used only in times of drought

Groundwater Modeling Overview

Simulate a range of withdrawals to meet agricultural needs during drought

Evaluate impacts to groundwater/ surface water

Assess impacts of pumping on groundwater quality

Assess uncertainty with model predictions

Groundwater Study Objectives

Potential mitigation techniques for users, if affected

Saline water encroachment from the coast.

Land surface subsidence

Induced migration of poor quality native groundwater that could result from increased groundwater use

Determine if additional groundwater can be developed without substantially affecting the current groundwater users and evaluate:

Comprehensive Groundwater Evaluation

Defines consequences of conjunctive useIdentifies mitigation needs and optionsUses more data and performs more data analyses than the GAMPredictions will contain confidence limits based on uncertainty associated in calibrated model Model will be developed at the spatial resolution supported by the data 0.1 to 0.5 mile variable grid anticipated

Stay tuned . . .