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Above the Woodbine: how deep the wells are

Home water wells completed in younger formations above the Woodbine in North and Central Texas vary a lot in depth: the middle half are 64 to 330 feet deep (median 160 ft, 1,739 wells drilled in the last 10 years), so look at the wells closest to the tract. In the state's model it is shale, chalk and marl. It carries the most weight in Bastrop County (100% of its wells), Bowie County (100% of its wells) and Milam County (100% of its wells). Estimated cost of a complete well at the median depth: $6,500 to $16,000.

Updated every day from Texas Water Development Board driller reports. Last update: November 11, 2026, using the state file of November 10, 2026.

Depth of wells in younger formations above the Woodbine, by countyThe dot is the median and the bar the middle half for each county. The table below has the figures.0200400600800 ftBastropBastrop: 240–404 ftBastrop: 300 ft300BowieBowie: 57–104 ftBowie: 74 ft74MilamMilam: 161–480 ftMilam: 360 ft360HuntHunt: 160–280 ftHunt: 200 ft200FanninFannin: 57–105 ftFannin: 63 ft63LeeLee: 258–642 ftLee: 458 ft458FallsFalls: 60–70 ftFalls: 65 ft65WilliamsonWilliamson: 35–180 ftWilliamson: 40 ft40Red RiverRed River: 75–411 ftRed River: 100 ft100DallasDallas: 36–60 ftDallas: 50 ft50KaufmanKaufman: 64–120 ftKaufman: 100 ft100EllisEllis: 56–85 ftEllis: 80 ft80

Under Texarkana, Bowie County

Dot: median. Bar: middle half (25th to 75th percentile). Counties with the most wells in this layer.

What this layer is

The state's Northern Trinity and Woodbine model treats everything above the Woodbine as a single layer: the Eagle Ford, Austin, Taylor and Navarro groups (mostly shale, chalk and marl) plus younger sands and river deposits where they exist. It is a catch-all, not one rock. In counties east and south of the Trinity outcrop, a home well in this layer is usually drawing from a younger local sand that this model does not separate.

Units the model puts in this layer: Eagle Ford, Austin, Taylor and Navarro groups, plus Tertiary and Quaternary deposits where present.

Source of the layers: TWDB's Northern Trinity and Woodbine model, with quarter mile cells, summarized here to about 1.3 miles.

Key figures

Typical depth (middle half)
64 to 330 feet
Median depth
160 feet
Deepest 10% are past
500 feet
Water level (median)
42 feet
1,467 wells
Yield (median)
20 gpm
1,422 wells, gallons per minute
Wells used
1,739
In the last 10 years
All years on file
3,941
median 157 ft, since 2000
Confidence
Standard (30 or more wells)

Counties where homes draw from this layer

Only counties with at least 10 wells in the layer. The share is of the county's wells that the model covers.

Depth of wells in younger formations above the Woodbine, by countyThe dot is the median and the bar the middle half for each county. The table below has the figures.0200400600800 ftBastropBastrop: 240–404 ftBastrop: 300 ft300BowieBowie: 57–104 ftBowie: 74 ft74MilamMilam: 161–480 ftMilam: 360 ft360HuntHunt: 160–280 ftHunt: 200 ft200FanninFannin: 57–105 ftFannin: 63 ft63LeeLee: 258–642 ftLee: 458 ft458FallsFalls: 60–70 ftFalls: 65 ft65WilliamsonWilliamson: 35–180 ftWilliamson: 40 ft40Red RiverRed River: 75–411 ftRed River: 100 ft100DallasDallas: 36–60 ftDallas: 50 ft50KaufmanKaufman: 64–120 ftKaufman: 100 ft100EllisEllis: 56–85 ftEllis: 80 ft80
Dot: median. Bar: middle half (25th to 75th percentile). Counties with the most wells in this layer.
CountyMedian depth (ft)WellsShare of the county's wells
Bastrop County300284100%
Bowie County74275100%
Milam County360210100%
Hunt County200161100%
Fannin County6311757%
Lee County458112100%
Falls County65108100%
Williamson County40817%
Red River County1006592%
Dallas County505882%
Kaufman County10058100%
Ellis County803824%
Bell County43357%
Limestone County26027100%
McLennan County652630%
Lamar County1002091%
Navarro County1552091%
Robertson County18515100%
Henderson County6012100%
Hill County470103%
Travis County92101%

Places where it is the main layer

Where it sits among the model's layers

From top to bottom, with the median depth of the home wells that draw from each:

Layer (state's model)RockMedian depth (ft)Wells
Above the Woodbineshale, chalk and marl1601,739
Woodbinesandstone with shale2601,037
Washita and Fredericksburglimestone, marl and clay2401,050
Upper Trinity (Paluxy and Glen Rose)sandstone, limestone and marl2809,322
Lower Trinity (Twin Mountains and Travis Peak)sandstone with shale and limestone34012,230

Depth over time

Home well depth in this layer has not changed meaningfully in 20 years: the median was 140 feet in 2003 to 2007 and 145 feet in 2021 to 2025 (a difference under 10% or within the margin of error).

PeriodMedian depth (ft)Wells
2001–2005160638
2006–2010147735
2011–2015165693
2016–2020150745
2021–20251451,021
2026228108

Common questions

How deep is a well in younger formations above the Woodbine?

Home water wells completed in younger formations above the Woodbine in North and Central Texas vary a lot in depth: the middle half are 64 to 330 feet deep (median 160 ft, 1,739 wells drilled in the last 10 years), so look at the wells closest to the tract.

What is younger formations above the Woodbine?

The state's Northern Trinity and Woodbine model treats everything above the Woodbine as a single layer: the Eagle Ford, Austin, Taylor and Navarro groups (mostly shale, chalk and marl) plus younger sands and river deposits where they exist. It is a catch-all, not one rock. In counties east and south of the Trinity outcrop, a home well in this layer is usually drawing from a younger local sand that this model does not separate.

How deep does the water stand in these wells?

When the wells were finished, the water stood a median 42 feet below the surface (1,467 wells), well above the bottom: the typical well holds about 118 feet of water.

What a well in this layer costs

At the median depth for this layer (160 feet), a complete home well would cost roughly $6,500 to $16,000: $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 (64 to 330 feet) the range runs from $4,000 to $26,500. 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 with a valid depth on their report. 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 92% 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 7,977 wells in the area of the state's Northern Trinity and Woodbine model (North and Central Texas) 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 74% of them, and that layer or the one next to it in at least 95%; among the 3,130 of those wells that the state places in a Trinity layer (Paluxy to Hosston) it is about 56%.

  • The layers come from the Texas Water Development Board's Northern Trinity and Woodbine model, with quarter mile cells, summarized here to about 1.3 miles. 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.
  • In this model every layer is at least 30 feet thick, even where the real rock is thinner or missing. Thin layers and the edges of the model are approximate.
  • Inside the Trinity this atlas does not name single model layers: it groups the Paluxy and Glen Rose (upper Trinity) and groups the Hensell, Pearsall and Hosston (lower Trinity, Twin Mountains and Travis Peak), because the check against the state's codes shows the method cannot separate them reliably.
  • "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/formations/younger-formations. License CC BY 4.0. https://doi.org/10.5281/zenodo.24126380.

Sources