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Dockum Group: how deep the wells are

Home water wells that end at or just below the base of the Ogallala, in the top of the Dockum, in the Panhandle, the South Plains and the Permian Basin vary a lot in depth: the middle half are 165 to 440 feet deep (median 250 ft, 6,009 wells drilled in the last 10 years), so look at the wells closest to the tract. In the state's model it is red mudstone, sandstone and conglomerate. It carries the most weight in Mitchell County (87% of its wells), Crane County (87% of its wells) and Scurry County (80% of its wells). Estimated cost of a complete well at the median depth: $9,000 to $21,500.

Be careful with this group: where our method names the Dockum, the state's own record agrees in only 33% of 4,542 wells (61% for the 1,168 with a screened interval on their report); most of the others are recorded as Ogallala wells. The typical well we put here barely passes the base of the Ogallala, so read it as "at or just below the base of the Ogallala, in the top of the Dockum", not as a confirmed formation.

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 the Dockum Group, by countyThe dot is the median and the bar the middle half for each county. The table below has the figures.0200400600 ftRandallRandall: 310–500 ftRandall: 460 ft460EctorEctor: 126–204 ftEctor: 160 ft160GainesGaines: 196–260 ftGaines: 229 ft229PotterPotter: 244–355 ftPotter: 290 ft290HowardHoward: 80–150 ftHoward: 112 ft112CraneCrane: 238–246 ftCrane: 240 ft240AndrewsAndrews: 115–130 ftAndrews: 120 ft120LubbockLubbock: 190–274 ftLubbock: 218 ft218ScurryScurry: 180–260 ftScurry: 240 ft240MartinMartin: 100–162 ftMartin: 135 ft135HaleHale: 225–343 ftHale: 292 ft292WardWard: 117–150 ftWard: 130 ft130

Under West Odessa, Ector County

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

What this layer is

The Dockum is red mudstone, sandstone and conglomerate more than 200 million years old (Triassic) that lies under the Ogallala and the Cretaceous rocks; drillers often call it the red beds. Its sandstones, mostly the lower ones (Santa Rosa), give water to some home wells, for example in Randall and Potter counties. Many wells that just reach the top of the Dockum still draw from the base of the Ogallala, and the state's records usually list them as Ogallala wells.

Units the model puts in this layer: upper Dockum Group (Cooper Canyon / Trujillo); lower Dockum Group (Santa Rosa / Tecovas).

Source of the layers: TWDB's High Plains Aquifer System model, with half mile cells, read here on a grid of about 1.2 by 1.4 miles.

Key figures

Typical depth (middle half)
165 to 440 feet
Median depth
250 feet
Deepest 10% are past
505 feet
Water level (median)
246 feet
3,050 wells
Yield (median)
15 gpm
2,679 wells, gallons per minute
Wells used
6,009
In the last 10 years
All years on file
14,410
median 230 ft, since 2001
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 the Dockum Group, by countyThe dot is the median and the bar the middle half for each county. The table below has the figures.0200400600 ftRandallRandall: 310–500 ftRandall: 460 ft460EctorEctor: 126–204 ftEctor: 160 ft160GainesGaines: 196–260 ftGaines: 229 ft229PotterPotter: 244–355 ftPotter: 290 ft290HowardHoward: 80–150 ftHoward: 112 ft112CraneCrane: 238–246 ftCrane: 240 ft240AndrewsAndrews: 115–130 ftAndrews: 120 ft120LubbockLubbock: 190–274 ftLubbock: 218 ft218ScurryScurry: 180–260 ftScurry: 240 ft240MartinMartin: 100–162 ftMartin: 135 ft135HaleHale: 225–343 ftHale: 292 ft292WardWard: 117–150 ftWard: 130 ft130
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
Randall County4602,40362%
Ector County1601,60557%
Gaines County22946913%
Potter County29019522%
Howard County11214444%
Crane County24011787%
Andrews County12011628%
Lubbock County2181023%
Scurry County24010180%
Martin County1359211%
Hale County2929041%
Ward County1306774%
Dallam County5355052%
Hartley County5804749%
Mitchell County1604787%
Garza County1104573%
Sterling County1204375%
Midland County165341%
Moore County5473419%
Borden County1403375%
Armstrong County2652627%
Lamb County2602520%
Reagan County3902223%
Dawson County1842014%
Deaf Smith County340179%
Briscoe County2361655%
Carson County3401519%
Nolan County1801565%
Dickens County1051430%
Winkler County2071240%
Glasscock County1801112%
Upton County3001119%

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
Ogallala Aquifersand, gravel, silt and caliche16112,389
Pecos Valley Aquifersand, gravel and clay18090
Edwards-Trinity and Rita Blanca (Cretaceous rock under the Ogallala)sand, sandstone and limestone1635,214
Dockum Groupred mudstone, sandstone and conglomerate2506,009

Depth over time

Home well depth in this layer has not changed meaningfully in 20 years: the median was 240 feet in 2003 to 2007 and 260 feet in 2021 to 2025 (a difference under 10% or within the margin of error).

PeriodMedian depth (ft)Wells
2001–20052501,546
2006–20102202,738
2011–20152003,753
2016–20202352,674
2021–20252603,240
2026310459

Common questions

How deep is a well in the Dockum Group?

Home water wells that end at or just below the base of the Ogallala, in the top of the Dockum, in the Panhandle, the South Plains and the Permian Basin vary a lot in depth: the middle half are 165 to 440 feet deep (median 250 ft, 6,009 wells drilled in the last 10 years), so look at the wells closest to the tract.

What is the Dockum Group?

The Dockum is red mudstone, sandstone and conglomerate more than 200 million years old (Triassic) that lies under the Ogallala and the Cretaceous rocks; drillers often call it the red beds. Its sandstones, mostly the lower ones (Santa Rosa), give water to some home wells, for example in Randall and Potter counties. Many wells that just reach the top of the Dockum still draw from the base of the Ogallala, and the state's records usually list them as Ogallala wells.

How deep does the water stand in these wells?

When the wells were finished, the water stood a median 246 feet below the surface (3,050 wells), close to the bottom: the typical well holds only about 4 feet of water.

What a well in this layer costs

At the median depth for this layer (250 feet), a complete home well would cost roughly $9,000 to $21,500: $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 (165 to 440 feet) the range runs from $6,500 to $33,000. 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 89% of these wells the report says where the water enters and we use the middle of that interval; for the rest we use the bottom of the hole, which tends to read one layer too deep.

How well it works: In 22,814 wells in the Texas part of the state's High Plains Aquifer System model (the Panhandle, the South Plains and the Permian Basin) where the State of Texas recorded the aquifer, the formation our method says the well draws from (as grouped on these pages) is the one the state recorded in about 75% of them; when it names the Dockum (4,542 wells), the state's record agrees only about 33% of the time, and most of the others are recorded as Ogallala wells.

  • The layers come from the Texas Water Development Board's High Plains Aquifer System model, with half mile cells, read here on a grid of about 1.2 by 1.4 miles. It is a regional model, not a survey of any lot.
  • The state's model has half mile cells; we read it on a grid of about 1.2 by 1.4 miles, Texas part only. Layers from version 1.01 (2015); the 2025 extension (1.02) did not change them. It is not a survey of any lot, so we give ranges.
  • Figures go by four groups: Ogallala; Pecos Valley; Edwards-Trinity and Rita Blanca (Cretaceous rock under the Ogallala; the Rita Blanca alone matched the state 19%); Dockum (upper and lower together: the state's codes almost never say which). The Edwards-Trinity group joins three aquifers in different places (High Plains around Lubbock, Plateau around Midland and Odessa, Rita Blanca in Dallam and Hartley): county and place pages name the local one where they can.
  • Dockum: when our method names the Dockum, the state's record agrees only 33% of the time over all years (61% for wells with a screened interval, which is 93% of home wells of the last 10 years); most of the rest are recorded as Ogallala wells. The median well we put in the Dockum ends about 18 ft under the base of the Ogallala as the model draws it. So these pages say "at or just below the base of the Ogallala, in the top of the Dockum", never a certain formation. The state's own 2025 report on this model says depth alone overstates the upper Dockum.
  • "Near or below the base" means the well ends near or below the base of the Dockum, or of the Ogallala where there is no Dockum (Permian red beds; Gray, Carson, Donley, Moore and north Potter counties). Half of these wells end within about 51 ft of the base, and the state usually records them as Ogallala or Dockum wells. That is not an error: the model simply ends there.
  • For old wells without a screened interval (bottom of the hole) the method is only a little better than always saying Ogallala (65% against 58%); with an interval it is 89% against 80%. Figures over all years carry that weakness; last 10 years figures rest almost entirely on intervals.
  • 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/dockum. License CC BY 4.0. https://doi.org/10.5281/zenodo.24126380.

Sources