What Future Do We Desire for the Trinity Aquifers?

Across the Hill Country, residents and visitors depend on the groundwater stored in the Trinity Aquifers as water supply and to provide baseflow through springs that keep iconic creeks and rivers flowing.  Residents have a voice through the regional planning process to discuss and set goals to guide the future we desire for the Trinity Aquifers.

Cypress Creek in downtown Wimberley

Desired Future Conditions, or DFCs, are a tool to coordinate groundwater management across groundwater conservation districts.  The DFC is a regional planning tool that does not supersede or take the place of local groundwater management put in place by local elected officials through groundwater conservation districts.  The individual Districts tailor their Rules and Bylaws to effectively manage and protect the local groundwater resources, and currently don’t have to rely on the DFC for more than a planning tool.

TWDB Desired Future Conditions Process Chart

Instead, the DFC is an agreed upon goal accepted by the groundwater conservation districts within a groundwater management area (GMA) and, it is an important part of a regional groundwater planning process that helps inform the State’s Water Plan.  In the Hill Country, GMA-9 is the group of groundwater conservation districts that manage the Trinity Aquifers.  Currently, one of GMA-9’s tasks is to reach consensus on a revised DFC for the Trinity Aquifers.

The WVWA submitted comments to the Chair and member GCDs of GMA-9 to encourage needed changes to the DFC.  We look forward to continuing the dialog, so science can further inform and sharpen policy.

June 30, 2021

Representatives of the Districts of Groundwater Management Area 9:

On behalf of more than 19,000 members of the Wimberley Valley Watershed Association, thank you for the opportunity to offer public comments toward Desired Future Conditions for Groundwater Management Area 9 joint planning, as provided by the Texas Water Development Board. WVWA may be headquartered in and primarily focused on the Hays Trinity Groundwater Conservation District in GMA 9, but our sphere of consideration includes a 31-county region that touches GMAs 7–13. We are keenly aware of the interrelated nature of water supply in Texas and advancing scientific understanding of groundwater and surface water interaction. The socioeconomic importance of water management is central to our state’s and GMA 9’s future. We believe a greater sense of urgency is needed to preserve groundwater for future generations.

WVWA Submitted Comments (pdf)

Groundwater Conservation Districts must consider a number of aquifer uses and conditions under Texas Water Code. Water supply needs and hydrological conditions are paramount, and so are environmental impacts that include spring flow and other groundwater and surface water interactions. Private property rights and socioeconomic impacts are equally valid. Finally, DFC feasibility and “any other relevant information” by law must be considered. Toward that end, please consider these entirely relevant comments in your joint planning decisions.

To begin, the Trinity Aquifer is distinctly different among its Upper, Middle, and Lower Trinity divisions. Desired Future Conditions should be distinguished separately and monitored accordingly. As it stands, the Desired Future Condition for the Trinity Aquifer currently stated as an “increase in average drawdown of approximately 30 feet through 2060” does not adequately protect availability of groundwater in GMA 9. Groundwater levels over the decade that this standard, a greater than doubling of the Modeled Available Groundwater, have shown an unacceptable decline. Moreover, Census 2020 will arrive too late to be included in planning, and observable population growth makes clear our projections need to be updated. New groundwater modeling is on the way. In the meantime, GMA districts should take a more conservative view and reduce drawdown to 0 to 4 feet until new data and upgraded modeling can be incorporated.

The argument by some that modeled available groundwater represents an unalterable commitment to that level or more fails on modeling for conservation. When wells fall to historic lows in mild drought conditions, models deserve scrutiny to ensure that groundwater does indeed remain available, as intended. Specific local measures and additional DFCs related to spring flows can further address disparity in groundwater drawdowns across districts. Overall groundwater system health cannot be reduced to a single average drawdown number. Spring flow is directly observable and superior to use as a drought trigger to protect groundwater resources.

To support these improvements, GMA 9 districts should develop and support the necessary science to establish and expand regional groundwater management zones for the critical areas that recharge springs and feed our vitally important creeks and rivers. Already, the Blanco River Aquifer Assessment Tool has been funded and will in a year or two provide our best model yet of the complicated groundwater and surface water interactions in the Trinity Aquifer. GMA 9 should account for obvious stresses on the groundwater system until the BRAAT is completed. Monitoring should be increased to better identify and track these stresses. Only the lack of severe drought since 2016 has tempered an already noticeable downtrend in median aquifer health.

Mining the aquifer according to outdated DFCs is unsustainable. Reasonable steps to reduce pumping and preserve access to groundwater for essential use exist and are widely available. Rainwater harvesting can completely replace more traditional water supply and fill any gap created by a reduction in the MAG. Graywater reuse and subsurface drip irrigation—as demonstrated in the construction and operation of Wimberley ISD’s Blue Hole Primary School—combine with rainwater and AC condensate to create a One Water system that reduces groundwater use by up to 90% compared to a nearly identical school in the district. Conservation of groundwater is a readily viable alternative to increased pumping and aquifer depletion. In some areas, aquifer storage and recovery, and even direct potable reuse offer further options. GCDs should actively support research and implementation of alternatives to fresh groundwater.

WVWA respectfully calls on the districts of GMA 9 to follow the science and monitoring, and discontinue an unsustainable status quo. The time is now to reconsider hydrological conditions and the adverse environmental impacts of current DFCs. Local districts should localize DFCs based on spring flow and interactions between groundwater and surface water. GMA 9 may be comparatively small geographically, but the diversity of its predominant Trinity Aquifer means that a single solution from Kerrville to Kyle creates disparities that threaten imminent socioeconomic hardship. Development continues apace with limited guidance by cities and counties. The burden lies on GMA 9’s districts to be creative in sustaining aquifer health. GMA 9 should make room for more fine-grained modeling and corresponding local management.

WVWA has been entrusted by our loyal supporters since 1996 to protect and preserve the quality and quantity of water in the Blanco River and Cypress Creek. From Jacob’s Well to Blue Hole to the Great Springs of Texas, we understand that groundwater means all water. The time has come for GMA 9 likewise to preserve and protect our groundwater. We must all use less and reuse more, and earnestly seek sustainable alternatives. WVWA has long been a partner with GCDs in that effort and through these supportive comments hopes to strengthen and deepen that relationship in GMA 9 and across Texas.

David Baker
Executive Director, WVWA

Submitted Comments and Resolutions

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