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Groundwater

GCDs GAMs

GMAsDFCs

MAGs

James A. BeachLBG-Guyton Associates

Brief History of Groundwater Management in Texas

• 1904 – “Rule of Capture”

• 1949 – Leg allows Districts

• 1951 – High Plains UWCD

• 1995 – Leg allows GMAs

• 2001 – TWDB designates GMAs

• 2005 – GCDs in GMAs required to set DFCs and TWDB determines MAG

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District Creation

GMAs

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GCDs, GMAs, RWPGs

Some History

• GCD- Groundwater Conservation Districts

• GAM – Groundwater Availability Model

• RWPG – Regional Water Planning Groups

• GMA – Groundwater Management Area

• DFC– Desired Future Condition

• MAG – Managed Available Groundwater

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Status

• GCDs are “preferred”

• 90% of groundwater usage is within districts

• Increase in the number of GCDs

• Increase in potential acquisitions/permits/restrictions

• Increased scrutiny of all permits

• Aquifer science really does matter

What is groundwater availability or MAG?

• the amount of groundwater available for use

• The State does not directly decide how much groundwater is available for use: GCDs will through the GMA process

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DFC Timeline & Approach

• DFCs are due to TWDB no later than Sept 2010

• Response time by TWDB to assess MAGs varies with workload

The GMA Process(condensed)

• GCDs in the GMAs set the DFCs and TWDB uses the GAMs to determine the MAG which RWPGs then use for planning and the GCDs use to permit

• Regulators, stakeholders, attorneys, consultants will continue to argue over details

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How it supposed to work

Groundwater Management

Area

GCD 4GCD 1

GCD 2 GCD 3

DFCMAG

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Approaches for Defining MAG

• Water Budget– DFC: Predetermined Decline

• Springflow or stream impact– DFC: Maintain Springs during Drought

• Water Quality – DFC: limited or no degradation

• Sustainability– DFC: long-term inflow = outflow

• Combination– DFC: Agency/stakeholder defined

Aquifer Schematic

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Examples

• Sustainability–several districts

• Water Budget–Ogallala districts (50/50)

• Springflow or stream impact–EAA, Barton Springs

• Water Quality – Gulf Coast area

Important observations(restating the obvious)

• Location still matters– Historical use does shape economies & perspectives• Sustainability (lifestyle, economy, environment)

• Environmental

• Aesthetic/recreational

– Future growth will drive demands• “No-fault” planning-development disconnect

• Water is only one of many factors

– Aquifer type• Confined/unconfined

• Recharge, transmissivity, storage

• Surface water interaction

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Important observations(restating the obvious)

• Groundwater perspectives and debates often stem from much more fundamental beliefs

–Private property/government intervention

–Stewardship (prioritization of people and environment)

–Sustainability

The Edwards Aquifer Experience

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The Edwards Experience

• Vital but limited resource

• Long historical use and future growth

• “DFC” - maintain springflow

• “MAG” - cap pumping and set rules (imperfect science, politics)

• Permits based on historical use

• Conflicts, Adjustments (adaptive management)

• 2007 SB3 (more adaptive management)

• Outcomes to date (market development, better science, surface water/groundwater balance)

• 15 years later, ongoing saga……

Region I – ahead of the game

• 2004 Planning

• Carrizo-Wilcox Aquifer

• “DFC” was defined

– no more than 50 feet of water level decrease (or 10% decrease in saturated thickness in unconfined section) by 2050

• Used TWDB GAM

• Managed Available Groundwater (MAG), was estimated based on Desired Future Condition (DFC).

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Region I Groundwater Supply

Historical InfoManaged Available Groundwater basedon Desired Future Condition (DFC)

Desired Future Condition Used for Region Water Planning

Region I lessons

• “DFC” was iterative

• GAMs and modeling process are imperfect but useful

• “MAG” targets were already busted in a few counties

• Adaptive management will be required

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A few unsettled issues

• Springflow related DFCs

• Model/data related limitations

• Adaptive management (takings)

• Established uses versus future demand

• Consistency of DFCs, MAGs, management plans and rules

Summary

• Groundwater permitting and management is changing

• It will continue to change as the GMA process plays out

• potential for complexity and disputes is much greater, especially in high demand areas

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Region I Status

• Carrizo-Wilcox – TWDB has done two GAM runs

– Varying DFCs

• Gulf Coast– TWDB has completed draft run for SE Texas GCD

– preliminary run by April 28

– Will assess impact of previous availability estimates

• TWDB - 16 GAM runs for various purposes

• Several GCDs doing separate studies

• Official MAGs won’t be ready for RWPG implementation

Recommendation

• Consultant will work with GCDs

• Summarize DFCs for each GCD/GMA

• Develop groundwater availability estimates based on:

– Proposed DFCs

– Results of GAM runs

– Projections from GCDs

– 2007 Plan

• Submit for RWPG approval by next meeting

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Photo courtesy: New Mexico Institute of Mining and Technology

Approaches

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GAM simplicity versus aquifer complexity

• GAMs are great tools

• Have limitations

• Will require updates

• More localized studies and tools may be required

Distribution of pumping and permits

• aquifers are not lakes

• where you drill and pump matters

• some areas not as productive

• Refinement and re-distribution of MAG within districts may be desired/required

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Imperfect but vital science

• we’re still learning

• to the degree that science can help maximize the value of groundwater, it will be important

• better science and ongoing studies will play a role in ensuring that maximum benefit is reaped from all groundwater by helping to optimize groundwater management

Potential DFC/MAG Challenges

• areas with no districts

• distribution of pumping and permits versus prior permits

• not perfect science –adjustments may be required

• GAM simplicity versus aquifer complexity

• long-term impacts

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Protests and Petitions

• Person with legally defined interest in groundwater

• Show evidence that DFC is unreasonable

• TWDB lead hearings and conflict resolution

• TCEQ petitions also possible

Planning in areas with no GCDs

• DFCs determined by GCDs in GMA

• RWPGs use MAG from DFCs

• rule of capture still applies

• no enforcement of MAGs

• However, could affect funding by TWDB, but not alternative funding

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Expected versus Actual

• Regionalization

–The degree will vary

• RWPGs use MAG

–No districts?

• GCD Targets with management plan

– Implementation?

Potential GAM Limitations

• Supporting Data– hydrogeology, hydraulic properties, heterogeneity

• Limiting Assumptions– Continuous porous media model

– “Lumped-layer” conceptualization

• Limits of Applicability– Stream-aquifer interactions

– Local use

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Summary

• Groundwater permitting and management is changing

• It will continue to change as the GMA process plays out

• potential for complexity and disputes is much greater, especially in high demand areas

GAM Aquifer Responses

Reduced pumping

Pumping Continues

Pumping stops after 25 years

Constant Pumping

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Water Levels in Carrizo Wells

Static Water Levels in Carrizo Aquifer Wells (Angelina and Nacogdoches Counties)

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th t

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ater

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et)

Other Tools

• Other Models• SAWS South-Central Carrizo-Wilcox Model

• LCRA-SAWS Gulf Coast model

• Other localized models

• Other scientific data• Used in absence of models or to augment models

• Examples

– Historical water level and usage data

– Geochemistry

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Water Levels in Simsboro Wells

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ater

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Wickson Creek Sp. UD Well 1, 2,756-3,056 feet

City of Bryan Well 10, 2,670-2,940 feet

City of Bryan Well 16, 2,402-2,852 feet

City of College Station Well 1, 2,520-2,960 feet

City of College Station Well 3, 2,430-2,920 feet

Texas A&M Well 7, 2,490-3,010 feet

Gulf Coast GAM(Pump 30 years, then stop)

Well Field

Surrounding wells

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Volumetric Budgets

Volumetric Budget(by district, county, or sub-aquifer)