An%20Interregional%20Water%20Solution%20with%20Conjunctive%20Use%20of%20Groundwater

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An Interregional Water Solution with Conjunctive
Use of Groundwater

• Haskell L. Simon
• President, Coastal Plains Groundwater
  Conservation District
• Vice President, Region K Water Planning Group

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SB1 (1997)Mandate for Statewide Water Plan

• 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

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The Essence of the SB1 Process
Today
Before
Bottom Up Approach
Top Down Approach
vs.
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SB1 Regional Approach

• 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 plan
• Regional Plans consolidated into the State Water
  Plan Water for Texas 2002
• Implementation of the Plan will require
  legislative and/or regulatory action.

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Regional Water Planning Areas
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Regional Planning Group Membership(11 Interest
Groups)

1. Public
2. Counties
3. Municipalities
4. Agricultural Interests
5. Environmental Interests

1. Industries
2. Small businesses
3. River Authorities
4. Water Districts
5. Water Utilities
6. Electrical Generating Utilities

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Projected Urban Agricultural Water Uses
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Total Water Demand by Type of Use (2003)
Year 2060
Year 2000
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Use by Source of Supply (2000)
GROUND-
WATER
35
SURFACE
WATER
65
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2050 Water Needs

• 2050 Shortfalls
• 160,000 acre-feet/yr of irrigation
• Some rural communities upstream of
• Highland Lakes (5,400 acre-feet/yr)

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2050 Water Needs
Region L

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

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Regional Cooperation Defines Project
LCRA-SAWS Water Project
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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 area
• The 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

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Project Summary

• Construct off-channel reservoirs to store surface
  waters
• Institute practices and improvements to reduce
  agricultures demand for water
• Install groundwater wells to serve agricultures
  needs during drought
• Create up to 150,000 acre-feet per year for SAWS
• Meet environmental requirements
• Study Period activities determine
  implementability and permitting

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LCRA-SAWS Water Project
Water for rural communities
More stable water levels in Highland Lakes
Lake Buchanan
Austin
Instream flows to maintain aquatic habitat
San Antonio
Water for agriculture
Freshwater inflows for Matagorda Bay
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LCRA SAWS Water Project
Colorado

• Develop 330,000 ac-ft of water by
• 1. Irrigation conservation
• Onsite and system improvements in districts

Columbus
Wharton
Wharton
Matagorda
Bay City
Matagorda Bay
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Legislation requires that in order for the
project to proceed, the project must ...

1. Protect and benefit basin interests
2. Be consistent with the state regional water plan
3. Provide inflows adequate to maintain the
   ecological health and productivity of Matagorda
   Bay
4. Maintain current instream river flow protections
5. Ensure that San Antonio practices stringent
   conservation measures
6. Provide for a broad public and scientific review
   process
7. Benefit stored water levels in Lakes Travis and
   Buchanan

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We are at the beginning of a multi-year,
comprehensive evaluation
Permitting Review Completion of Studies
Permit Submittal Continuation of Studies
Technical Study Plan Development
Technical Studies
2002
2010
2004
2007-2008
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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

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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

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Groundwater Study Objectives
Determine if additional groundwater can be
developed without substantially affecting the
current groundwater users and evaluate

• 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

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Comprehensive Groundwater Evaluation

• Defines consequences of conjunctive use
• Identifies mitigation needs and options
• Uses more data and performs more data analyses
  than the GAM
• Predictions 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

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Stay tuned . . .