ground-water resources and management of the … · management of the guadalupe groundwater...

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GROUND-WATER RESOURCES AND MANAGEMENT OF THE

GUADALUPE GROUNDWATER CONSERVATION DISTRICT

Prepared For

Guadalupe County Groundwater Conservation District

Seguin, Texas

August 2002

LBG-GUYTON ASSOCIATES Professional Ground-Water and Environmental Services

1101 S. Capital of Texas Highway, Suite B-220 Austin, Texas 78746

DECE,vEn n AP~ iO 2 2012 U

BY: . \,pm .•

CHARLES W. KREITLER W. JOHN SEIFERT, JR. JOHN B. ASHWORTH JAMES BEACH BRUCE K. DARLING

BRAD L. CROSS ANDREW C.A. DONNELLY ERIC K. McALPINE JOHN W. NELSON KRISTlE L, PERSKY ALLAN R. STANDEN WILLIAM G. STEIN

Mr. Robin Dwyer

LBG-GUYTON ASSOCIATES PROFESSIONAL GROUND-WATER AND

ENVIRONMENTAL ENGINEERING SERVICES

1101 S, CAPITAL OF TEXAS HIGHWAY SUlTEB-220

AUSTIN, TX 78746-6437 512-327-9640

FAX 512-327-5573

August 14,2002

Guadalupe County Groundwater Conservation District 109 W. Court Seguin, TX 78155

Dear Mr. Dwyer:

ROBERT LAMONICA R,O, SLAYBACK WILLIAM K. BECKMAN DAN C, BUZEA J. KEVIN POWERS JOI·IN NAsa, JR. FRANK J, GETCHELL JEFFREY B. LENNOX

WILLIAM B. KLEMT

Transmitted herewith is our report, "Ground-Water Resources and Management of the Guadalupe County Groundwater Conservation District."

firm.

a call.

This report was prepared principally by me with some assistance from other of our

If you have any questions regarding the report or results of the study, please give me

Yours sincerely,

LBG-GUYTON ASSOCIATES

William B. Klemt Senior Consultant

A Division of Leggette, Brashears & Graham, Inc.

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TABLE OF CONTENTS

INTRODUCTION ......................................................................................................................... 1

Location and Extent of Study area .............................................................................................. 1 Purpose and Scope ....................................................................................................................... 1 Aclmowledgements ..................................................................................................................... 2

CARRIZO-WILCOX AQUIFER ................................................................................................ 2

Water-Bearing Strata ................................................................................................................... 2 Recharge, Discharge and Movement ........................................................................................... 3 Hydraulic Characteristics ............................................................................................................ 4 Chemical Quality ......................................................................................................................... 4

GROUND-WATER A V AILABILITy ......................................................................................... 5

GROUND .. WATER MANAGEMENT ....................................................................................... 6

Ground-Water Management Considerations ............................................................................... 6 Drought Contingency Planning ................................................................................................... 7

CONCLUSIONS AND RECOMMENDATIONS ...................................................................... 8

Monitoring ................................................................................................................................... 8 I

\ Ground-Water Management Considerations ............................................................................... 9 Ground-Water Management Zones ............................................................................................. 9 Water Marketing ........................................................................................................................ 10 Drought Contingency Planning ................................................................................................. 11

SELECTED REFERENCES ..................................................................................................... 13


Table 1

Figure

TABLE (at end of report)

Proposed Water-Level Observation Wells

LIST OF FIGURES (at end of report)

1 Texas Water Development Board Water Level Observation Wells

2 Texas Water Development Board Results of Water-Chemistry Analyses of Ground Water from the Carrizo-Wilcox Aquifer (1 970-Present)

3 Generalized Geologic Section A-A'

4 Approximate Altitude of the Base of the Carrizo-Wilcox Aquifer

5 Approximate Water Saturated Thickness of the Carrizo-Wilcox Aquifer

6 Approximate Altitude of the Base of the Carrizo Aquifer

7 Approximate Altitude of the Top of the Can'izo Aquifer

8 Approximate Water Saturated Thickness of the Carrizo Aquifer In Guadalupe County

9 Approximate Altitude of Water Levels in the Can'izo-Wilcox Aquifer, Year 2002

10 Approximate Artesian Pressure Head Above the Top of the Carrizo Aquifer

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GROUND-WATER RESOURCES AND MANAGEMENT OF THE GUADALUPE COUNTY GROUNDWATER CONSERVATION DISTRICT

INTRODUCTION

The anticipated future water demands of Schertz and Seguin, Texas, and other small

communities in Guadalupe County may require some sources other than the Edwards aquifer and

surface water from the Guadalupe River. One possible alternative is the development of wells in

Guadalupe County, which would supply water from the Carrizo-Wilcox aquifer. Previous

studies by the Texas Water Development Board and others have shown that significant quantities

of water (greater than 10,000 acre-feet per year) maybe able to be developed from the aquifer

for municipal supplies. Management and protection of the ground-water resources of the

Carrizo-Wilcox aquifer in Guadalupe County is the responsibility of the Guadalupe County

Groundwater Conservation District.

Location and Extent of Study Area

The study area consists of the southeastern portion of Guadalupe County where the

CaITizo-Wilcox aquifer is present. It consists of approximately one-half of Guadalupe County.

Figures 1 and 2 show following: (a) the location of the District; (b) aerial extent of the Carrizo

Wilcox aquifer; and (c) water wells utilized by the Texas Water Development Board to track

changes in water levels and water quality in the Carrizo-Wilcox aquifer.

Purpose and Scope

The primary objective of this study is to improve the basic understanding of the ground

water conditions in the District and identify possible management strategies in order to regulate

the production of ground-water from the CaITizo-Wilcox aquifer to ensure adequate water for the

future.

The scope of work includes the following: (a) review readily available ground-water data

and reports for that portion of Guadalupe County underlain by the Carrizo-Wilcox aquifer; (b)

estimate the aquifer's parameters (penneability, transmissivity, and storage); (c) make estimates

of recharge to the aquifer; (d) conduct a work shop with the District's Board Members to

( improve the basic understanding of the hydrogeology of the aquifer in Guadalupe County; (e)


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identify wells which may be used by the District to track changes in water levels; and (f) prepare

a report which summarizes the findings and makes recommendations with regard to management

of the District.

Acknowledgements

We wish to express our grateful acknowledgement to all individuals and organizations

who participated in this study. The cooperation of federal and state agencies, especially the

Texas Water Development Board, is also gratefully acknowledged.

Special acknowledgement is extended to Mr. Craig Caldwell and Mr. Randy Williams of

the Texas Water Development Board. These men generously provided basic data, technical

info=ation, and advice, which contributed toward the successful completion of this study.

Finally, appreciation is expressed to Mr. Ronald Naumann, Mr. Hilmar Blumberg, and

Mr. Robin Dwyer of the Guadalupe County Groundwater Conservation District. Their helpful

cooperation and interest contributed toward the successful completion of this investigation and a

better understanding of the Carrizo-Wilcox aquifer in Guadalupe County.

CARRIZO-WILCOX AQUIFER

The name "Carrizo" was first applied to the thick, massive sand beds that overlie the

sands, silts and clays of the Wilcox Group in the vicinity of Carrizo Springs, Texas around the

tum of the 19th century. Because the sands of the Wilcox Group are hydraulically connected

with the Carrizo Sand in Guadalupe County, the te= "Carrizo-Wilcox aquifer" is often used.

Water-Bearing Strata

The water-bearing strata of the Carrizo-Wilcox aquifer are marine and continental in

origin and consist mainly of cross-bedded river sand, beach sand, silt, clay, and lignite. These

sediments were deposited by large, fluvial-deltaic river systems which were sourced in the

Rocky Mountains and Ouachita-Arbuckle Mountains (Ayers and Lewis, 1985). Figure 3 shows

the position of the aquifer in the subsurface and geologic fo=ations, which bound the aquifer

above and below. Overlying the Carrizo Sand are the clays and interbedded glauconitic sands of

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the Reklaw FOlmation. Underlying the Wilcox are the clays and shales of the Midway

( formation.

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The San Marcos Arch, which generally trends northwest-southeast parallel to the

Guadalupe and Caldwell County line, is a structural high which affected the deposition and

faulting of the Carrizo-Wilcox in Guadalupe County. The aquifer thins over the arch and

thickens to the north and south. The altitude of the base of the Canizo-Wilcox aquifer with the

associated faulting and the water-saturated thickness of the aquifer is shown on Figures 4 and 5,

respectively.

In Guadalupe County, the Carrizo aquifer is the preferred source of ground water with

only minor amounts of water being withdrawn from the sands and clays of the Wilcox. The

altitude of the base and top of the aquifer and its water-saturated thickness are shown on Figures

6, 7, and 8, respectively.

Recharge, Discharge and Movement

The Camzo-Wilcox aquifer is recharged by precipitation and certain situations by

seepage from lakes, streams, and rivers crossing the outcrop area. Significant factors which

control the amount of water recharged include: topography of the land surface, amount and kind

of vegetative cover, soil characteristics and hydraulic conductivity (penneability) of the rocks

and soils exposed in the outcrop. Surface topography exerts a strong control on ground-water

movement within the aquifer, with recharge occurring in the outcrop along drainage divides and

moving down gradient into the aquifer and/or discharging to topographic lows along river basins.

The percentage of the average annual precipitation rate that enters the Camzo-Wilcox .

outcrop and is transmitted downdip is often referred to as effective recharge. Calculations made

by Shafer (1966) indicate the effective recharge is on the order of an inch per year or

approximately three percent of the average annual precipitation rate in Guadalupe County. The

estimated I inch of effective recharge applied to the outcrop of the Camzo-Wilcox aquifer in

Guadalupe County is roughly equivalent to 20,000 acre-feet per year. However, it is estimated

that approximately one-half or more of the 20, 000 acre-feet is recharged in the outcrop ofthe

Camzo aquifer. This is roughly 2 to 3 inches of the average annual precipitation rate applied to

the outcrop of the Canizo.

Ground water in the Carrizo-Wilcox aquifer moves downward from the recharge zone


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(outcrop) to the zone of saturation and then generally in the direction of the water-level gradient

to points of discharge (wells, livers, springs, seeps, etc.). On the order of 1,500 acre-feet of

ground water is presently being pumped from the aquifer.

Figure 9 illustrates the water-level surface of the aquifer, which is an imaginary surface

that everywhere coincides with the static water level in the aquifer. These water levels indicate

the general direction of ground-water movement is southeastward toward Gonzales County and

that there is some flow toward the Guadalupe and San Marcos Rivers. Losses of potential

recharge include seepage losses on the outcrop and evapotranspiration.

Hydraulic Characteristics

An aquifer's hydraulic characteristics are generally described in terms of its coefficients

of transmissivity and storage. These are determined generally for the Carrizo-Wilcox aquifer by

conducting pumping tests in selected wells and from well performance tests conducted by water

well ddlling and servicing companies. Transmissivity and storage are a measure of an aquifer's

ability to transmit and store water, and can be used to determine proper well spacing,

interference between pumping wells and to predict water-level drawdowns around pumping

wells.

Little is known about the hydraulic characteristics of the Wilcox underlying Guadalupe

County, pdncipally because of the lack of suitable wells in which to observe these

charactedstics. A few well pumping rates of as high as 400 to 500 gallons per minute (gpm)

have been reported. However, large wells are the exception as most of the inventoried Wilcox

wells are reported to have small well yields.

Chemical Quality

Large well pumping rates ranging from 500 to as high as 1,500 gpm can be expected

from the Carlizo aquifer in southeastern Guadalupe County. An aquifer test which was

conducted in southeastern Guadalupe County where the Camzo aquifer is under artesian

conditions indicates the transmissivity of the Camzo is on the order of 40,000 to 50,000 gallons

per day per foot (gpd/ft). In the outcrop where the Camzo is under water-table conditions, the

transmissivity of the aquifer is less. Coefficients of storage for the Carrizo aquifer probably

range from 0.0001 to 0.001 and from 0.10 to 0.30 in the artesian and outcrop portions of

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Guadalupe County, respectively. The outcrop and artesian portions of the Carrizo-Wilcox

C aquifer are shown on Figure 10.

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In general, water quality of the Carrizo aquifer in Guadalupe County is good and meets

the National Primary Drinking Water Regulations Standards required for public health.

However, secondary standards for pH and iron may not be met. Water exceeding secondary

standards poses an aesthetic problem, not a health risk. Additionally, hydrogen sulfide and

methane gas may be found locally within the Carrizo aquifer.

The water chemistry of the Wilcox is quite variable, and in general, the water quality is

not as good as the Can'izo aquifer (Figure 2). Dissolved solids, chloride, and sulfate can be

much higher and may not meet state standards.

Some of the local variability seen in the water-chemistry results for the aquifer

(especially the Wilcox) are probably dependent on proper well completions and sampling

procedures used. For comparison purposes, the water chemistry values shown on Figure 2 can

be compared with the Texas Natural Resource Conservation Commission's (TNRCC) Interim

Use Drinking-Water Standards for Public Health. TNRCC's standards are as follows: a)

dissolved solids, 1,000 milligrams per liter (mg/l); b) chloride, 300 mg/l; and c) sulfate, 300

mg/l.

GROUND-WATER AVAILABILITY

The amount of ground water that can be developed by wells from the Carrizo-Wilcox

aquifer in the District on a long-term basis is directly related to the ability of the aquifer to

transmit water from the outcrop to points of discharge. In addition to the aquifer's effective

recharge, there is the assumption that a small amount of water in storage can be withdrawn on a

constant annual basis.

The amount of ground water from the Carrizo Wilcox aquifer which may be utilized for

future development for the next twenty (20) years without causing excessive water-level declines

within the District is approximately 12,600 acre-feet per year (acre-ftlyr) less the 1,500 acre-ftlyr

which is presently being pumped (public water supplies, almost 1,000 acre-ftlyr). Projected

ground-water demands on the aquifer are expected to double by the year 2020 (about 3,000 acre-

LEG-GUYTON ASSOCIATES

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ft/yr). Therefore, on the order of 10,000 acre-ftlyr is available for future development over the

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The 12,600 acre-ft/yr estimate was derived from tabulations prepared by Muller and Price

(1979). The most favorable area to develop this water is from the Ca11'izo aquifer in southeastern

Guadalupe County where artesian conditions exist.

GROUND-WATER MANAGEMENT

The Guadalupe County Groundwater Conservation District has adopted preliminary

rules, and the Texas Water Development Board is presently reviewing the District's

"Management Plan". The District's "Drought Management Plan" will be developed within

approximately one year. The remarks below are pertinent to ground-water management within

the District.

Ground-Water Management Considerations

The Guadalupe County Groundwater Conservation District has been given great C flexibility in determining what powers they will exercise in the regulation of large wells (wells

which produce over 25,000 gallons per day). This allows for a strong active district to serve the

needs of Guadalupe County. The following are important considerations and activities with

regard to what the District may do in developing a regulatory strategy: (a) well spacing and

ground-water production may be regulated; (b) require permits for drilling, equipping and

completion of water wells; (c) maintain water-well drilling, production, rainfall, water-level, and

water-chemistry records; and (d) commission ground-water studies.

One of the District's important goals is to limit water-level declines in the Can'izo-Wilcox

aquifer. It has been proposed that the District regulate ground-water production in order to meet

this goal in one of two ways: (a) allow 2 acre-feet of water per year to be produced per acre for

large wells; or (b) allow a much smaller ground-water allocation per acre in order that all

properties within the District would have a ground-water allowable for large wells. In each case,

the ground-water allowable could be used or sold should there be a water market. However, in

each case, the District should limit total ground-water production to 12,600 acre-feet per year (


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from the aquifer.

( In the first case, only a limited number of property owners located in southeastern

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Guadalupe County would be able to utilize their allowable for production or take advantage of

the water market. This is because southeastern Guadalupe County is the most favorable area for

ground-water production from the Carrizo aquifer. At this location, the Carrizo consists mostly

of fine to coarse, loose sand, aud is capable of very large well pumping rates. The number of

surface acres which may be presently utilized for this purpose would be about 5,000 acres.

In the second case, all of the landowners located over the Carrizo-Wilcox aquifer would

be able to utilize their allowable or participate in the water market. However, those areas not

located in southeastern Guadalupe County are not as favorable for ground-water production and

their allowable would less than 1 inch per acre to either sell or use.

Drought Contingency Planning

A "good" drought contingency plan is one that is tailored to the unique conditions and

circumstances of the District. There is a stepwise process that can be followed to develop au

effective drought contingency plan for the Carrizo-Wilcox aquifer to satisfy state requirements.

There are six basic steps, which are as follows:

I. Involve the public in the development of the plan. This can be done through public

notification and information about the plan, and public involvement in plan

development.

2. Assess the District's vulnerability to drought and define criteria for initiating or

terminating (triggering criteria) drought response measures. The pIau should include

specific criteria for determining when water supply, water demand, or other

conditions warrant implementation or termination of drought response measures. For

example, implementation of drought response measures might be initiated when

water levels are declining at a rate faster than expected or water demand equals or

exceeds some value or percentage ofthe District's production allowable (12,600 ac

ftlyr) over some defined period of time (e.g., trigger levels beginning when daily

water demand exceeds 60 percent oflarge well capacity or the Distlict's production


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allowable).

3. Detennine drought response measures. This could include curtailment ofpelmitted

production rates for large wells and/or mandatory restrictions on certain water uses

within the District.

4. Design a multistage plan. The plan should provide for the implementation of drought

response measures in successive stages (usually three to five stages) geared to the

severity of the situation. For example, the District may increase public awareness

during mild conditions up to reducing pennitted production rates for large wells

during critical conditions.

5. Adopt the plan through administrative rules by the District's Board of Directors.

6. Review and/or update the plan at least every 5 years.

CONCLUSIONS AND RECOMMENDATIONS

The Carrizo-Wilcox aquifer's ground-water resources in Guadalupe County have only

been partially developed. On the order of 12,600 acre-ftlyr of ground water is available,

primarily from the aquifer. In the area of the Wilcox outcrop, most wells are domestic-stock

wells with small well yields. However, present pump age is on the order of 1,500 acre-ft/yr from

the Carrizo-Wilcox aquifer and is expected to increase to about 3,000 acre-ftlyr by the year 2020.

Therefore, on the order of 10,000 acre-ftlyr over the next 20 years is available for future

development, primarily from the Canizo aquifer.

Monitoring

The District should establish a water-level program in order to monitor water-level

changes in the Carrizo-Wilcox aquifer. It is recommended that five wells be selected and

measured in January and August of each year. The location and records of six wells, which may

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LEG-GUYTON ASSOCIATES

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be suitable, are shown on Figure 1 and the attached table. However, these wells will need to be

inventoried before it can be detennined they are suitable. The District's measurements, when

combined with the Texas Water Development Board's water-level program measurements, over

the next 5 years should provide the necessary infonnation to define unacceptable water-level

declines, drought conditions, and water-level drought triggers in order to prepare a drought

contingency plan.

In addition to a water-level program, the District should develop a rainfall monitoring

program. The rainfall stations should be located on or close to the outcrop of the Carrizo aquifer.

These stations may help in detennining drought conditions and estimating the recharge to the

Carrizo within the District.

Ground-Water Management Considerations

The District's Board of Directors, in developing the District's management and

regulatory ground-water program, should promote water conservation, provide public

infonnation, issue water-well pennits, take enforcement action where necessary, and cooperate

with adjacent ground-water districts and other water agencies.

( In administering a permit program that limits pumping from the Carrizo-Wilcox aquifer

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to 12,600 acre-ftJyr, the Board of Directors should be aware that historical and present pump age

from the Carrizo aquifer in Guadalupe County and adjacent counties are causing regional water

level declines of about one (1) foot per year within the District. Increased future development of

the Carrizo in these areas will increase the rate of regional water-level decline. In addition, it is

expected that future development of the Carrizo aquifer will have little impact on the Wilcox

aquifer within the District. The Board should also consider such things as spacing, production,

water-level declines in the vicinity of the proposed well and neighbors' wells, and location within

or distance to the Carrizo outcrop. The Board should also be ready to deny a water-well permit

when the permit application is not in accordance with the rules and guidelines of the District and

to reduce permitted pumping rates when water levels are declining at a rate faster than

anticipated.


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Ground-Water Management Zoues

There are three possible management zones within the District. These zones are as (

follows: (a) the outcrop of the Wilcox; (b) the outcrop of the Carrizo and those areas down dip

where the aquifer is under water-table conditions; and (c) those areas where the Carrizo aquifer

is under artesian conditions. Figure 10 generally shows these areas.

The outcrop of the Wilcox should not require a great deal of management effort. This is

because, in general, the aquifer will not support large-capacity wells, and the water quality is not

as good as the Carrizo. For management purposes, new and existing wells should be permitted

so that the District knows where they are and about how much they are pumping on an annual

basis.

Where the Carrizo aquifer is under water-table conditions (outcrop and areas immediately

down-dip of the outcrop), management will be required in order that the aquifer in the outcrop is

not dewatered extensively. The District should detennine how much water levels will be

allowed to decline and over what time period. Perhaps a maximum of 50 tol00 feet of water

level decline could be tolerat(jd over a period of25 years (about 2 to 4 feet per year). In order to

manage the zone in this way, the District would have to require the following: (a) pennits; (b)

applicants for pennits should demonstrate the impact their project would have on water levels (

before a pennit is granted; and (c) measurement of water-level observation wells in order that the

rate of water-level decline can be monitored. If the rate of water-level decline exceeds the

acceptable rate, then pumping rates may have to be reduced for those large wells regulated by the

District.

The last zone to consider is where the Carrizo aquifer is under artesian conditions. For

practical purposes, this is where the aquifer has 50 or more feet of artesian head above the top of

the aquifer. This portion of the aquifer should be managed so that water levels are not allowed to

fall very far below the top of the aquifer. Management would require pennits, demonstrations by

the applicant, and measurement of water levels in observation wells in order to track declines and

reduce well yields if necessary.

Water Marketing

The District's present rules allow landowners to market up to 2 acre-ftfyr of ground water

per surface acre owned. This is a relatively simple rule to enforce and allows the District to limit


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ground-water pumping to the recommended production allowable (12,600 ac-ft/yr). However,

only a limited number of landowners in southeastern Guadalupe County will benefit from the

sale or lease of their water. There are alternatives, which should be considered.

The District could set the production allocation for each acre over the Carrizo-Wilcox

aquifer within the District by dividing the recommended production allowable (12,600 ac-ftlyr)

by the number of acres over the Carrizo-Wilcox in the District. The production allocation per

acre would be small (less than I inch of water per acre per year). However, each landowner over

the Carrizo-Wilcox within the District could participate in the water market ifhe sold or leased

his water right to a "water developer."

Another approach would be to establish the production allocation for each acre based on

the saturated thickness of the Carrizo aquifer in the outcrop and artesian areas. This would

exclude those landowners located over the outcrop of the Wilcox and increase the production

allocation for those landowners located over the Canizo outcrop and artesian areas. In this case,

the production allocation would probably range from less than 1 inch to as much as 3 inches of

ground water per acre depending on location.

The following is expected with regard to the two alternatives: (a) landowners located

( over. the outcrop of the Carrizo-Wilcox aquifer would probably lease or sell their ground-water

(

rights; (b) a maximum of about five or six Carrizo wells would be completed in the favorable

area (southeastern Guadalupe County) if all of the ground-water rights could be obtained from

landowners; and ( c) these alternatives will be more difficult to administer because of the large

number of landowners.

Drought Contingency Planning

There are six steps in preparing a drought contingency plan. The most important

elements from a ground-water hydrology point of view are as follows: (a) assess the District's

vulnerability to drought and define triggering criteria; (b) detennine drought response goals and

measures; and (c) design the plan.

Water-level drawdown measurements in the District that may be used as drought triggers

during drought conditions have not been identified. However, it is recommended that over the

next 5 years rainfall stations and water levels in observation wells be measured in order that

these measurements may be used to revise the initial drought management plan.


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It is recommended the initial plan design include tlu'ee trigger levels based on water

demands. The first, second and third levels would begin when daily water demands exceeded 60 (

percent, 70 percent, and 80 percent, respectively, of the District's large-well future development

capacity (10,000 ac-ft/yr, primarily from the Carrizo aquifer).

The recommended response stages are as follows: (a) Trigger Levell - public awareness

and notification of drought conditions; (b) Trigger Level 2 - use of water rate incentives or

penalties (e.g., surcharges for excess use) for water suppliers receiving water from large wells

located within the District; and (c) Trigger Level 3 - water rationing (e.g., water allocation on a

per-household basis) imposed on water suppliers receiving water from large wells located within

the District). Permits for new large wells should incorporate provisions for water rate incentives

and water rationing as described.

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SELECTED REFERENCES

Ayers, W. B., and A. H. Lewis, 1985, The Wilcox Group and Carrizo Sand (Paleogene) in east

central Texas: depositional systems and deep-basin lignite: University of Texas Bureau of

Economic Geology.

Duffin, G. 1. and G. R. Elder, 1979, Variations in specific yield in the outcrop ofthe Carrizo

Sand in south Texas as estimated by seismic refraction: Texas Department of Water

Resources Report 229.

Hamlin, H. S., 1988, Depositional and ground-water flow systems of the Carrizo-Upper Wilcox,

south Texas: University of Texas Bureau of Economic Geology Report ofInvestigations

175.

( Klemt, W. B., G. 1. Duffin, andG. R. Elder, 1976, Ground-water resources of the Carrizo

(

aquifer in the Winter Garden area of Texas: Texas Water Development Board Report

210, Vol. 1.

Shafer, G. H., 1966, Ground-water resources of Guadalupe County, Texas: Texas Water

Development Board Report 19.

Turner Collie & Braden Inc., 1999, Handbook for drought contingency planning for retail public

water suppliers: workshop handbook prepared for the Texas Natural Resource

Conservation Commission.


TABLEt

PROPOSED WATER-LEVEL OBSERVATION WELLS

Well Reported Latitude Longitude Year Depth of Water- Altitude of Number Owner Completed Well Bearing Land Water Level Remarks

(feet) Unit Surface (feet)

Measuremeut Date from LSD

. (feet) 67-18-603 LemAllen 294150 974548 - 180 Wilcox 405 -18.64 05-26-1970 Unused livestock and

-17.98 01-16-1976 irrigation well. Reported yield of 400 gpm.

67-19-706 Glenwood 293917 974415 1967 357 Wilcox 451 -69.00 07-20-1967 Tested at 150 gpm on Warnicke 7/20/67. Pump set at 289

feet. 67-27-401 New Birth 293251 974345 1961 27 Carrizo 384 -18.50 07-25-1974 Dug welL

Baptist Church

67-27-702 Dusker 293226 974452 1954 462 Carrizo 450 -80.00 12-00-1954 --Harris

67-33-803 J. O. Starcke 292252 975723 -- 140 Carrizo 585 -125.00 08-00-1964 Cased to bottom Reported strong supply.

67-33-901 RH. 292249 975308 1957 1,030 Carrizo 570 -190.80 05-22-1959 Reported yield 1,000 gpm. : Wernert Estate

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NOTES FROM TWDB GCGCD MANAGEMENT PLAN CHANGES

1. pg 5 10.4 Needs to be clarified as to how many new wells will be evaluated. Want to be able to accomplish the goal

2. pg 6 Methodology for tracking the process is required - suggested text is on the diskette

3. Section 12 pg 6 Need more up to date data - include 1999 data (on diskette)

4.

5.

pg 7 -14

pg 7 15

Delete table 5 & clarify

clarify

6. Have to go thm the orignal process - hearing, GBRA review

7. need to show plan effective for 10 years.

8. pg 5 10.6 add another objective - so that a continuing activity can be seen

ground-water resources and management of the … · management of the guadalupe groundwater...

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