Aquifer, Travis, Williamson, and Bell 

Counties, Texas, March–June 2005

Data Series 125

U.S. Department of the Interior

U.S. Geological Survey
Cover. Edwards aquifer well in southern Williamson County (photograph by M.L. Greenslate, U.S. Geological Survey, June 

2005).
Water-Level Altitudes in Wells Completed 

in the Northern Segment of the Edwards 

Aquifer, Travis, Williamson, and Bell 

Counties, Texas, March–June 2005

By Sachin D. Shah 

U.S. Department of the Interior

U.S. Geological Survey

In cooperation with the Texas Commission on Environmental Quality 

Data Series 125
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2005

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Suggested citation:

Shah, S.D., 2005, Water-level altitudes in wells completed in the northern segment of the Edwards aquifer in Travis,

Williamson, and Bell Counties, Texas, March–June 2005: U.S. Geological Survey Data Series Report 125, 6 p.
iii

Contents

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Well Selection and Data Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Water-Level Altitudes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Figure

1. Map showing northern segment of the Edwards aquifer and sites of wells in which water levels 

measured, March–June 2005 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Table

1. Well locations and water-level altitudes in the northern segment of the Edwards aquifer, 

March–June 2005 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Vertical and Horizontal Datums

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).
Water-Level Altitudes in Wells Completed 

in the Northern Segment of the Edwards 

Aquifer, Travis, Williamson, and Bell 

Counties, Texas, March–June 2005

By Sachin D. Shah 

Abstract

During March–June 2005, the U.S. Geological Survey, in 

cooperation with the Texas Commission on Environmental 

Quality (TCEQ), measured water levels in 80 Edwards aquifer 

wells in the outcrop of the northern segment of the aquifer in 

Travis, Williamson, and Bell Counties. Public-supply and 

private wells were selected in areas where outcrop water-level 

data were sparse. The altitude data can be used in the TCEQ 

Source Water Assessment and Protection program to help 

delineate zones of capture around sources of public water supply. Altitudes range from about 490 to about 935 feet above 

North American Vertical Datum of 1988. 

Introduction

This report, prepared by the U.S. Geological Survey 

(USGS) in cooperation with the Texas Commission on Environmental Quality (TCEQ), presents water-level altitudes 

obtained from 80 wells completed in the outcrop of the northern 

segment of the Edwards aquifer in Travis, Williamson, and Bell 

Counties (fig. 1) during March–June 2005. The objective of the 

study was to compile a database of water-level altitudes for the 

TCEQ Source Water Assessment and Protection (SWAP) program in parts of the outcrop area where water-level-altitude data 

are sparse. The TCEQ implemented the SWAP program to 

determine the susceptibility to chemical constituents of the 

State’s public water sources (Texas Natural Resource Conservation Commission, 2005). The altitude data can be used to help 

delineate zones of capture around sources.

The Edwards aquifer in Central Texas commonly is 

divided into the San Antonio segment, the Barton Springs segment, and the northern segment (fig. 1). The northern segment 

consists of the Edwards aquifer north of the Colorado River. 

Baker and others (1986) presents a comprehensive description 

of the geohydrology of the northern segment of the Edwards 

aquifer. From that report, the outcrop of the northern segment 

encompasses an area of about 500 square miles and consists 

mostly of limestone with some interbedded marl. These rocks 

typically are dense, grayish to white, and massive. Where 

present, soils on the outcrop typically are brown, silty to clayey 

loams that range in thickness from negligible to about 5 feet. 

The thickness of the northern segment of the aquifer, which has 

been influenced by erosion and faulting, ranges from negligible 

to about 450 feet. From the outcrop, the aquifer dips to the eastsoutheast at an average slope of 70 to 75 feet per mile beneath 

rocks that confine the Edwards aquifer and yield little to no 

water. Recharge to the northern Edwards aquifer occurs primarily by downward percolation of rainfall on the outcrop. Solution features such as honeycombing, sinkholes, and caverns 

allow for rapid infiltration of water. Water levels fluctuate over 

a wide range in most areas because of the rapid rates of recharge 

and, to a lesser extent, variations in rates of discharge. 

The author acknowledges well owners for allowing USGS 

personnel access to their property and their wells.

Well Selection and Data Collection

Wells for water-level measurement were selected from 

available databases of well information compiled by the Texas 

Water Development Board (2005), the TCEQ (J. Meyer, Texas 

Commission on Environmental Quality, written commun., 

2005), and the USGS (M.L. Greenslate, U.S. Geological Survey, written commun., 2005). Public-supply and private wells 

were selected in areas where outcrop water-level data were 

sparse. On the basis of available well depth and aquifer top and 

bottom altitude data, only wells completed in the Edwards aquifer outcrop were included. If well depth was unavailable, the 

decision to include a well was made on the basis of other information in the database. The wells selected for water-level 

measurement have comparable depths and screened intervals. 

Access to wells was provided by municipalities, private owners, 
2 Water-Level Altitudes in Wells Completed in the Northern Segment of the Edwards Aquifer, Texas, March–June 2005

Water-Level Altitudes in 

Wells Completed in the 

Northern Segment of the 

Edwards Aquifer, Texas, 

March–June 2005

and ground-water conservation districts. Water-level measurements were obtained by electronic sensor, steel tape, or calibrated airline. Public-supply wells are pumped daily but were 

shut down for 12 hours prior to measurement so that static 

water-level measurements could be made. 

Water-Level Altitudes

Water-level altitudes and associated data for the 80 wells 

in which measurements were made during March–June 2005 

are listed in table 1. Altitudes range from about 490 to about 935 

feet above NAVD 88. Depths to water range from about 5 to 

265 feet below land surface. Well depths among wells with 

known depths range from 26 to 450 feet below land surface.

References

Ashworth, J.B, and Hopkins, Janie, 1995, Aquifers of Texas: 

Texas Water Development Board Report 345, 69 p.

Baker, E.T., Slade, R.M., Jr., Dorsey, M.E., Ruiz, L.M., and 

Duffin, G.L., 1986, Geohydrology of the Edwards aquifer in 

the Austin area, Texas: Texas Water Development Board 

Report 293, 215 p.

Texas Natural Resource Conservation Commission [former 

name of TCEQ], 2005, Source Water Assessment and Protection program (SWAP)—SWAP objectives and overview: 

accessed July 1, 2005, at http://www.tnrcc.state.tx.us/

permitting/waterperm/pdw/swap/swap.html 

Texas Water Development Board, 2005, Water information, 

integration, & dissemination: accessed July 1, 2005, at 

http://www.twdb.state.tx.us/home/index.asp 
Figure 1 3

Figure 1

Figure 1. Map showing northern segment of the Edwards aquifer and sites of wells in which water levels measured, March–June 2005.

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US 290

US 183

US 183

CR 620

STATE 360

IH 35

IH 35

STATE 71

CR 2222

STATE 111

STATE 95

US 79

STATE 29

IH 35

US 190

STATE 138

STATE 332

STATE 1325

STATE 1

STATE 275

WILLIAMSON COUNTY

TRAVIS COUNTY

BELL COUNTY

0 3 6 9 12 MILES

97o50'

30o55'

97o33'

30o28'

EXPLANATION

Outcrop (Ashworth and Hopkins, 1995) 

Subcrop (N.A. Houston, U.S. Geological 

Survey, written commun., 2005)

Well site (see table 1)

Albers equal-area projection, Datum NAD 83

TEXAS

Northern 

segment

Edwards aquifer in Central Texas

Barton Springs segment

San Antonio 

segment

Colorado River
Table 1 Table 1. Well locations and water-level altitudes in the northern segment of the Edwards aquifer, March–June 2005—Continued. State well number USGS site identifier Latitude (ddmmss.ss) Longitude (ddmmss.ss) Well depth (feet below land surface) Water use Land-surface altitude (feet above NAVD 88) Drill date Water-level measurement date W

(f

Travis County 58–35–403 302720097431701 302720.00 974317.00 95.0 domestic 840.0 1964 04/16/2005 

58–35–405 302717097431901 302717.00 974319.00 100.0 unused 845.0 1959 04/26/2005 

58–35–415 302652097430501 302649.00 974303.00 112.0 stock 830.0 -- 04/26/2005 

58–35–702 302257097444701 302312.00 974444.00 49.0 unused 873.0 1935 05/12/2005 

Williamson County 58–18–605 304046097452001 304045.00 974519.00 140.0 domestic 856.60 2005 06/06/2005 

58–19–104 304324097423001 304324.00 974230.00 140.0 domestic 801.31 2005 06/06/2005 

58–19–105 304247097431101 304236.00 974235.00 100.0 domestic 794.80 2005 04/26/2005 

58–19–204 304336097403201 304336.00 974032.00 126.0 domestic 810.0 05–20–1976 05/11/2005 

58–19–316 304242097394801 304242.00 973948.00 -- public supply 739.17 -- 04/26/2005 

58–19–407 304031097431201 304031.00 974312.00 86.3 domestic 870.06 -- 05/13/2005 

58–19–408 304021097431301 304021.00 974313.00 86.3 domestic 852.44 -- 05/13/2005 

58–19–409 304001097431901 304001.00 974319.00 45.0 domestic 781.02 -- 05/13/2005 

58–19–410 304008097431601 304008.00 974316.00 26.0 domestic 802.85 -- 05/13/2005 

58–19–411 304003097432101 304003.00 974321.00 45.0 domestic 782.65 -- 05/13/2005 

58–19–502 304203097403201 304203.00 974032.00 124.0 domestic 740.0 1975 04/26/2005 

58–19–506 304154097404401 304154.00 974044.00 110.0 domestic 750.0 1978 05/11/2005 

58–19–507 304118097403101 304117.00 974023.00 185.0 public supply 770.0 05–11–1979 04/26/2005 

58–19–518 304130097401201 304130.00 974012.00 -- domestic 742.72 -- 05/13/2005 

58–19–519 304132097400601 304132.00 974006.00 115.0 domestic 733.63 -- 05/13/2005 

58–19–521 304036097401301 304036.00 974013.00 -- public supply 728.59 -- 04/26/2005 

58–19–522 304012097412101 304011.00 974121.00 130.0 domestic 751.60 2005 06/06/2005 

58–19–603 304139097395501 304139.00 973955.00 72.0 irrigation 700.0 -- 04/26/2005 

58–19–619 304117097384001 304117.00 973840.00 220.0 public supply 691.0 03–18–1985 05/10/2005 

58–19–626 304217097400001 304217.00 974000.00 105.0 irrigation 705.0 04–06–1984 05/10/2005 

58–19–628 304108097392401 304108.00 973924.00 200.0 public supply 733.0 12–05–1986 05/10/2005 

Table 1. Well locations and water-level altitudes in the northern segment of the Edwards aquifer, March–June 2005. [dd, degrees; mm, minutes; ss, seconds; --, no data]
58–19–632 304102097384001 304102.00 973840.00 -- stock 660.0 -- 05/10/2005 58–19–633 304117097391201 304117.00 973912.00 -- domestic 679.80 -- 05/13/2005 

58–19–634 304145097394601 304145.00 973946.00 -- irrigation 688.10 -- 05/13/2005 

58–19–635 304146097393701 304146.00 973937.00 -- irrigation 693.85 -- 05/13/2005 

58–19–636 304145097394001 304145.00 973940.00 -- irrigation 688.82 -- 05/13/2005 

58–19–637 304037097383801 304037.00 973838.00 -- domestic 712.16 -- 04/26/2005 

58–19–802 303812097405001 303812.00 974050.00 102.0 unused 750.0 1912 04/26/2005 

58–19–803 303809097404901 303809.00 974049.00 186.0 public supply 750.0 1952 04/26/2005 

58–19–805 303859097400901 303901.00 974009.00 175.0 public supply 680.0 12–09–1957 04/26/2005 

58–19–901 303919097385801 303919.00 973858.00 184.0 irrigation 680.0 1971 05/10/2005 

58–19–914 303925097393801 303925.00 973938.00 100.0 domestic 705.0 -- 05/10/2005 

58–26–808 303032097481501 303032.00 974814.00 150.0 domestic 874.91 2005 06/06/2005 

58–27–213 303702097401301 303702.00 974013.00 205.0 domestic 775.0 04–06–1973 04/25/2005 1

58–27–214 303629097411601 303629.00 974116.00 100.0 public supply 785.0 03–08–1977 05/11/2005 

58–27–221 303710097405101 303710.00 974051.00 200.0 public supply 753.0 1982 04/26/2005 

58–27–536 303247097403201 303247.00 974032.00 140.0 domestic 716.49 2005 06/29/2005 

58–27–610 303230097395901 303230.00 973959.00 140.0 domestic 717.97 2005 06/29/2005 

58–27–721 303104097431601 303036.00 974311.00 120.0 domestic 797.81 2005 04/22/2005 

58–27–814 303101097415401 303101.00 974154.00 222.0 public supply 750.0 1940 04/22/2005 

58–27–819 303117097421301 303108.00 974206.00 203.0 public supply 749.0 07–25–1978 04/22/2005 

58–27–824 303132097422601 303132.00 974226.00 135.0 public supply 775.0 05–11–1979 04/22/2005 

58–27–829 303132097422602 303132.00 974226.00 140.0 public supply 775.0 03–15–1979 04/22/2005 

58–27–838 303152097420301 303152.00 974203.00 115.0 domestic 745.74 2005 06/06/2005 

58–27–839 303057097402301 303057.00 974023.00 190.0 unused 702.65 -- 04/14/2005 

58–34–119 302844097503501 302844.00 975034.00 60.0 domestic 976.43 2005 06/06/2005 

58–34–305 302834097455101 302833.00 974552.00 65.0 unused 895.0 04–19–1980 04/22/2005 

58–34–309 302925097462001 302925.00 974620.00 140.0 domestic 910.10 2005 06/29/2005 

58–34–621 302707097461101 302700.00 974536.00 180.0 domestic 889.88 2005 04/22/2005 

Table 1. Well locations and water-level altitudes in the northern segment of the Edwards aquifer, March–June 2005—Continued. 

State

well

number

USGS site

identifier

Latitude

(ddmmss.ss)

Longitude

(ddmmss.ss)

Well depth

(feet below

land

surface)

Water

use

Land-surface

altitude

(feet above

NAVD 88)

Drill

date

Water-level

measurement

date

W

(f
58–35–102 302817097430101 302818.00 974301.00 46.0 industrial 775.0 -- 04/26/2005 58–35–105 302801097430801 302801.00 974308.00 70.0 industrial 780.0 1970 04/26/2005 

58–35–107 302810097430301 302810.00 974303.00 70.0 industrial 783.0 1969 04/26/2005 

58–35–112 302947097440301 302923.00 974348.00 140.0 domestic 817.50 2005 04/22/2005 

Bell County 58–04–302 305917097313901 305917.00 973139.00 148.0 domestic 680.0 12–09–1973 05/16/2005 

58–04–307 305805097310601 305805.00 973106.00 125.0 domestic 611.0 10–15–1970 05/16/2005 

58–04–508 305649097323501 305649.00 973235.00 97.0 public supply 618.0 03–14–1979 05/16/2005 

58–04–604 305718097314401 305720.00 973146.00 128.0 public supply 602.0 01–01–1972 05/16/2005 

58–04–605 305729097320801 305729.00 973208.00 100.0 domestic 630.0 05–26–1979 05/20/2005 

58–04–606 305728097315801 305728.00 973158.00 84.0 domestic 612.0 03–17–1971 05/20/2005 

58–04–609 305703097315901 305703.00 973159.00 74.0 domestic 590.0 09–24–1971 05/20/2005 

58–04–623 305624097321101 305626.00 973215.00 180.0 public supply 640.0 04–07–1992 03/01/2005 

58–04–702 305457097353601 305457.00 973536.00 95.0 unused 730.0 07–24–1980 03/01/2005 

58–04–811 305257097341401 305257.00 973414.00 250.0 public supply 787.25 -- 05/25/2005 1

58–04–812 305242097340701 305242.00 973407.00 231.0 public supply 811.09 -- 05/25/2005 2

58–04–813 305307097344001 305307.00 973440.00 -- irrigation 773.18 -- 05/31/2005 1

58–04–814 305324097342601 305324.00 973426.00 -- irrigation 754.50 -- 05/31/2005 1

58–04–815 305406097335701 305406.00 973357.00 -- irrigation 722.46 -- 05/31/2005 

58–05–102 305913097295801 305913.00 972958.00 152.0 domestic 612.0 04–23–1971 05/16/2005 

58–05–103 305850097294401 305850.00 972944.00 157.0 domestic 589.0 10–31–1971 05/16/2005 

58–05–204 305956097265601 305956.00 972656.00 222.0 unused 510.0 06–03–1972 03/03/2005 

58–11–303 305221097393201 305221.00 973932.00 -- domestic 887.66 -- 05/31/2005 

58–11–908 304714097374301 304714.00 973743.00 293.0 public supply 930.26 -- 05/25/2005 2

58–11–909 304725097373101 304725.00 973731.00 450.0 public supply 934.39 -- 05/25/2005 3

58–12–407 304931097363701 304931.00 973637.00 357.0 public supply 902.05 -- 05/25/2005 2

58–12–410 304933097364501 304933.00 973645.00 350.0 public supply 890.69 -- 05/25/2005 2

Table 1. Well locations and water-level altitudes in the northern segment of the Edwards aquifer, March–June 2005—Continued. State well number USGS site identifier Latitude (ddmmss.ss) Longitude (ddmmss.ss) Well depth (feet below land surface) Water use Land-surface altitude (feet above NAVD 88) Drill date Water-level measurement date W

(f
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Austin, TX 78754–4733

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