The Texas aquifer map — whose water is at stake in your county?

About 55 percent of the water used in Texas — for farming, industry, and drinking — comes from underground.^[1] Nine major aquifers and 22 minor aquifers lie beneath the state. Most Texans get their tap water from one of five of them. If a data center in your county files for a large well permit, the aquifer it draws from is the single most important fact on the application.

The five aquifers that matter most

Each of these five covers at least one county where a hyperscale data center is under review or under construction in 2026.

• Edwards (Balcones Fault Zone). Feeds San Antonio, New Braunfels, San Marcos, and the springs of central Texas. The recharge zone — where rainfall soaks into the aquifer — sits across the Hill Country. Counties served: Bexar, Comal, Hays, Kendall, Travis, Kinney, Medina, Uvalde.^[2]
• Trinity. Runs from Dallas–Fort Worth south through the I-35 corridor. Counties served: Johnson, Parker, Hood, Hays, Comal, Kendall, Bandera, and the western edge of Williamson.
• Carrizo-Wilcox. Stretches in a wide band from Dimmit County to the Arkansas line. Counties served: Bastrop, Caldwell, eastern Williamson, Kaufman, Hunt, Wood, and many more in East Texas.
• Ogallala. The Panhandle and South Plains. Counties served: Armstrong, Haskell, Lubbock, Hale, and more than 30 others. This is the aquifer under Google's rural Panhandle site and other announced AI-infrastructure locations.
• Gulf Coast. A broad system underlying the coastal plain from the Louisiana border to below Corpus Christi. Counties served: Harris, Galveston, Fort Bend, Montgomery, Jefferson, Brazoria, and more.

Priority counties and which aquifer they pump from

For the twenty Texas counties Stand is tracking for active or proposed data-center projects, the primary aquifer is as follows.

Who actually controls the water

A county commission can approve a rezoning for a data-center campus. But whether a facility can legally pump millions of gallons a day from underground is usually decided by a different body: a Groundwater Conservation District (GCD).

Groundwater Conservation Districts are local units of government created under Chapter 36 of the Texas Water Code.^[3] They set rules for large withdrawals, issue production permits, and set what state law calls "desired future conditions" for the aquifer. Not every Texas county has a GCD. Among the priority counties, the pattern is roughly:

• Counties with a GCD (GCD permits control): Bastrop (Lost Pines GCD), Caldwell (Plum Creek GCD), Hays (Hays Trinity / Barton Springs–Edwards Aquifer), Williamson (Central Texas / Clearwater UWCD), Comal (Edwards Aquifer Authority covers portions), Kendall (Cow Creek GCD), Parker (Upper Trinity GCD), Wise (Upper Trinity GCD), Hood (Upper Trinity GCD), Johnson (Prairielands GCD), Hunt (partial). These are the districts where a large-well permit can be formally contested.^[4]
• Counties with no GCD or special authority: Harris (Gulf Coast area — regulated through the Harris-Galveston Subsidence District instead), Dallas, Tarrant, Collin, Denton, Rockwall, Kaufman, Ellis. In these counties, the municipal water utility, the TCEQ, or a subsidence district handles permitting, and the private "rule of capture" still allows landowners to drill on their own property subject to utility rules.
• Edwards Aquifer Authority (EAA) is a special-purpose district created by the Legislature in 1993. It governs withdrawals from the San Antonio segment of the Edwards Aquifer — which means Bexar, Medina, Uvalde, and parts of Comal and Hays.^[5]

A rezoning vote can happen at the county commission. But the water vote happens at the groundwater district. Residents who only attend one may miss the more important one.

How to use this map in practice

If you are tracking a specific data-center proposal, three documents will answer nearly every water-related question:

1. The well log filed with the TWDB for the project's intended parcel. This says how deep, what aquifer, and projected yield.
2. The production permit application filed with the Groundwater Conservation District (if one has jurisdiction). This discloses peak-day withdrawal and any conditions imposed.
3. The water-supply agreement with the local utility (if the project is using municipal water). This is usually attached to the city council or utility-board agenda.

All three are public records. Any Texas resident may request them under the Texas Public Information Act.