Water wells in the Hill Country Underground Water Conservation District
Home water wells inside the Hill Country Underground Water Conservation District (Gillespie County, Texas) are typically 178 to 365 feet deep (median 240 ft, 1,957 wells drilled in the last 10 years). No single layer dominates: 51% draw from the Middle Trinity and 22% end near or below the base of the Trinity, according to the state's Hill Country Trinity model (TWDB). The model covers 68% of those wells (1,334). Drillers reported 147 new home wells in 2025, less than half the peak of 310 in 2021. Estimated cost of a complete well at the median depth: $8,500 to $21,000.
Updated every day from Texas Water Development Board driller reports. Last update: November 11, 2026, using the state file of November 10, 2026.
Under the center of the Hill Country UWCD
District boundary from TWDB's file current as of November 2019. Later changes are not shown.
Digging in…
Home wells in and around the Hill Country UWCD
Each dot is a home well from a state driller report, colored by depth. Tap one for its details and official report. Tap an empty spot to see what is under that point.
Well depth (ft)
- <100
- 100
- 200
- 300
- 400
- 600
- 800+
Dark line: the district boundary (TWDB, 2019)
Green: aquifer mapped by the state
Key figures
- Typical depth (middle half)
- 178 to 365 feet
- Median depth
- 240 feet
- Deepest 10% are past
- 540 feet
- Water level (median)
- 112 feet
- 1,517 wells
- Yield (median)
- 23 gpm
- 1,671 wells, gallons per minute
- Wells used
- 1,957
- In the last 10 years
- Counties
- 1
- All years on file
- 4,388
- median 238 ft, since 2001
- Confidence
- Standard (30 or more wells)
When the wells were finished, the water stood a median 112 feet below the surface (1,517 wells).
New home wells per year
Drillers reported 147 new home wells in 2025, less than half the peak of 310 in 2021.
Show the data table
| Year | Wells |
|---|---|
| 2002 | 179 |
| 2003 | 192 |
| 2004 | 173 |
| 2005 | 204 |
| 2006 | 231 |
| 2007 | 190 |
| 2008 | 137 |
| 2009 | 112 |
| 2010 | 98 |
| 2011 | 122 |
| 2012 | 128 |
| 2013 | 118 |
| 2014 | 137 |
| 2015 | 165 |
| 2016 | 154 |
| 2017 | 191 |
| 2018 | 158 |
| 2019 | 164 |
| 2020 | 175 |
| 2021 | 310 |
| 2022 | 305 |
| 2023 | 188 |
| 2024 | 187 |
| 2025 | 147 |
| 2026 | 119 |
Which formation the wells draw from
No single layer dominates: 51% draw from the Middle Trinity and 22% end near or below the base of the Trinity, according to the state's Hill Country Trinity model (TWDB). The model covers 68% of those wells (1,334).
| Layer (state's model) | Share | Wells | Typical depth (ft) |
|---|---|---|---|
| Middle Trinity | 51% | 675 | 181–470 |
| Near or below the base of the Trinity | 22% | 288 | 180–457 |
| Upper Trinity | 14% | 188 | 165–241 |
| Edwards Group | 13% | 177 | 180–240 |
| Lower Trinity | <1% | 6 | 650 |
For 95% of these wells the report says where the water enters (the screen or the open hole), and we use the middle of that interval.
Places with the most wells in the district
| Place | Median depth (ft) | Middle half (ft) | Wells | Main layer |
|---|---|---|---|---|
| Harper | 265 | 210–345 | 237 | Edwards Group |
| Fredericksburg | 177 | 138–235 | 233 | Middle Trinity |
| Stonewall | 282 | 180–432 | 102 | Near or below the base of the Trinity |
Counties
Depth over time
New home wells in the district are deeper than 20 years ago: the median went from 222 feet (2003 to 2007) to 245 feet (2021 to 2025), 10% more. Deeper wells do not always mean the water dropped: a driller may be going for another layer, better water or more reserve.
| Period | Median depth (ft) | Wells |
|---|---|---|
| 2001–2005 | 220 | 852 |
| 2006–2010 | 225 | 768 |
| 2011–2015 | 240 | 670 |
| 2016–2020 | 235 | 842 |
| 2021–2025 | 245 | 1,137 |
| 2026 | 275 | 119 |
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Common questions
How deep are wells in the Hill Country UWCD?
Home water wells inside the Hill Country Underground Water Conservation District (Gillespie County, Texas) are typically 178 to 365 feet deep (median 240 ft, 1,957 wells drilled in the last 10 years).
Which formation do wells in the district draw from?
No single layer dominates: 51% draw from the Middle Trinity and 22% end near or below the base of the Trinity, according to the state's Hill Country Trinity model (TWDB). The model covers 68% of those wells (1,334).
What does a groundwater conservation district do?
In Texas, districts are the local authority over groundwater: they can require registration or permits for new wells, set spacing from other wells and property lines, and limit pumping. Each district writes its own rules, so ask the Hill Country Underground Water Conservation District before drilling inside it.
What a well costs here
At the median depth for the district (240 feet), a complete home well would cost roughly $8,500 to $21,000: $25 to $60 per foot for drilling, casing and seal, plus $2,500 to $6,500 for the pump, pressure tank, controls and hookup at the well. Across the whole middle half of depths (178 to 365 feet) the range runs from $7,000 to $28,500. This is TerraFunded's estimate from published Texas prices, not a quote, and it leaves out trenching and the line to the house. Get prices from at least two licensed drillers.
How these numbers are made
We count new and replacement domestic (home) wells whose coordinates fall inside the district boundary. We use the last 10 years when there are at least 30 wells; otherwise all since 2001. The median is the middle well and the middle half runs from the 25th to the 75th percentile.
To tell which layer a well draws from, we take the ground elevation at its location, subtract the depth of the interval where water enters (or the bottom of the hole when the report does not give one) and see which layer of the state's model that point falls in.
For 95% of these wells the report says where the water enters (the screen or the open hole), and we use the middle of that interval.
How well it works: In 2,665 wells in the Texas Hill Country where the State of Texas recorded the aquifer, our estimate of the formation the well draws from names the same layer of the state's model in about 76% of them, and that layer or the one next to it in at least 98%.
- The layers come from the Texas Water Development Board's Hill Country Trinity model, with 1 mile cells. It is a regional model, not a survey of any lot: between one model point and the next, the real depth of each layer can differ.
- "Near or below the base of the Trinity" means the well reaches the bottom of the model or passes it, often by tens of feet. Older rock that the model does not include may lie there.
- We never use the model's water levels. The water level on this page is the one each driller measured when the well was finished.
These are depths of real wells drilled nearby, not a promise about any property. Groundwater can change over short distances and with drought. A licensed water well driller can tell you what to expect on a specific tract.
Read the full methodology · Download the data (CSV, CC BY 4.0)
How to cite
TerraFunded (2026). Texas Well Atlas: Underground. From Texas Water Development Board driller reports and groundwater availability models (data as of November 10, 2026). https://terrafunded.com/wells/districts/hill-country-underground-water-conservation-district. License CC BY 4.0. https://doi.org/10.5281/zenodo.24126380.
Sources
- Submitted Driller's Reports database, Texas Water Development Board (TWDB) (file of November 10, 2026)
- Groundwater Availability Model for the Hill Country portion of the Trinity Aquifer System, Texas. Jones, I.C., Anaya, R., and Wade, S.C., Texas Water Development Board, 2009, GAM v2.01 (MODFLOW-96). TWDB groundwater availability model.
- Groundwater conservation district boundaries, TWDB (current as of November 2019)
- Ground elevation: Terrain Tiles (Mapzen), Registry of Open Data on AWS
- TWDB well report viewer (each well's official report)