PLUM CREEK CONSERVATION DISTRICTPROPOSED
Groundwater Management Plan
10/22/2018

PLUM CREEK CONSERVATION DISTRICTP.O. Box 328
Lockhart, Texas 78644
Phone: 512 / 398-2383
Fax: 512 / 398-7776
Email: info@pccd.org
Website: www.pccd.org
President: James A. Holt, Jr.; Vice-President: James O. Lipscomb;
Directors: Lucy Knight, Ben Twidwell, Fred Rothert, Peter Reinecke
PROPOSED

Groundwater Management Plan
TABLE OF CONTENTS
1.

DISTRICT MISSION

2.

TIME PERIOD OF THIS PLAN

3.

BACKGROUND
1.

Introduction

2.

Policy3.

Governing Board

4.

Daily Operations

5.

Topography

6.

Location and Extent

7.

Water Resources

4.

GROUNDWATER RESOURCES

5.

MANAGEMENT ZONES

6.

PRODUCTION AND SPACING OF WELLS7.

MANAGEMENT OF GROUNDWATER SUPPLIES8.

ACTIONS, PROCEDURES, PERFORMANCE AND PLAN IMPLEMENTATION

9.

METHODOLOGY FOR TRACKING DISTRICT PROGRESS IN ACHIEVING MANAGEMENT GOALS

10.

MANAGEMENT GOALS, OBJECTIVES, & PERFORMANCE STANDARDS

10.1

Efficient Use of Groundwater

10.2

Controlling and Preventing Waste of Groundwater

10.3

Control and Prevent Subsidence

10.4

Conjunctive Use of Surface and Groundwater

10.5

Develop a Management Strategy to Address Drought Conditions

10.6

Address Natural Resource Issues That Impact the Use and Availability of
Groundwater and Which are Impacted By the Use of Groundwater

10.7

Conservation of Groundwater including Recharge Enhancement, Rainwater
Harvesting, Brush Control, and/or Precipitation Enhancement of Groundwater
Resources in the District

10.8

Mitigation & Desired Future Conditions of Groundwater Resources

10.9

Desired Future Conditions of Groundwater Resources

10.10

Alternative Supply

11.

PROJECTED TOTAL DEMAND FOR WATER WITHIN THE DISTRICT12.

PROJECTED SURFACE WATER SUPPLIES WITHIN THE DISTRICT13.

WATER NEEDS WITHIN THE DISTRICT14.

WATER MANAGEMENT STRATEGIES WITHIN THE DISTRICT15.

AMOUNT OF GROUNDWATER BEING USED IN THE DISTRICT ON AN ANNUAL BASIS

16.

ANNUAL AMOUNT OF RECHARGE FROM PRECIPITATION TO THE GROUNDWATER RESOURCESWITHIN THE DISTRICT.

17.

ANNUAL VOLUME OF WATER THAT DISCHARGES FROM THE AQUIFER TO SPRINGS AND
SURFACE WATER BODIES.

18.

ESTIMATE OF THE ANNUAL VOLUME OF FLOW INTO THE DISTRICT, OUT OF THE DISTRICT,AND BETWEEN AQUIFERS IN THE DISTRICT.

19.

ESTIMATE OF MODELED AVAILABLE GROUNDWATER IN DISTRICT BASED ON DESIRED FUTURE
CONDITIONS.

20.

GEOLOGY MAP OF PCCDPLUM CREEK CONSERVATION DISTRICTGROUNDWATER MANAGEMENT PLAN
1. DISTRICT MISSION
The Plum Creek Conservation District (PCCD) mission for groundwater management is to conserve and preserve
groundwater availability and protect permitted and exempt groundwater users, by gathering information about
groundwater conditions and uses within the District; obtaining information from surrounding Groundwater Districts toassist in understanding groundwater availability within Plum Creek’s area; by using that information to adopt Rules
consistent with state law in order to maximize the beneficial development and use of the groundwater resources on asustainable basis in keeping with the desired future conditions of aquifers within Plum Creek Conservation District’s
jurisdictional area; and by then enforcing these adopted Rules. The District will accomplish this mission by identifying
aquifers within the District; and then by (1) determining zones of the various aquifers within the District, (2) imposing
spacing requirements, (3) limiting production, (4) requiring permits for non-exempt wells and groundwater production, (5)noting information on exempt wells, (6) establishing water drawdown levels, (7) monitoring aquifer levels andproduction, (8) making appropriate adjustments to allowable and permitted production as more data become available, and(9) encouraging conservation to limit pumping. These actions are designed to extend the quantity and preserve the qualityof the water available in the aquifers in Caldwell and Hays counties regulated by the District. PCCD is committed toprotecting, conserving, and preventing waste of the groundwater resources in its District for the benefit of the citizens,
economy and environment.
2. TIME PERIOD OF THIS PLAN
This plan will become effective upon adoption by the PCCD Board of Directors and approval as administratively
complete by the Texas Water Development Board. The plan will remain in effect for five (5) years after the date of
approval or until a revised plan is adopted and approved, or as otherwise directed by the Texas Legislature.

13. BACKGROUND
The PCCD is situated in parts of Caldwell and Hays Counties. The District was created as a Water Control and
Improvement District in the 55th Texas Regular Legislative Session in 1957 with the passage of Senate Bill 289 under theprovisions of Section 59, Article XVI of the Texas Constitution. The enabling statute provided the District with thepower to control, conserve, protect, distribute and utilize the storm and floodwaters and unappropriated flow ofPlum Creek and its tributaries as a Water Control and Improvement District. In 1989 the original 1957 legislation wasamended to additionally authorize the District, upon approval of the qualified voters of the District, to exercise thepowers and duties imposed under what is now Chapter 36 of the Texas Water Code, for the preservation, conservation,
protection, recharge, and prevention of waste and pollution of the underground water of the District except in those areasof the District that were part of the Barton Springs-Edwards Aquifer Conservation District or the Edwards Underground
Water District on January 1, 1989. The voters in the District approved the implementation of the powers granted by theLegislature after the 1989 amendment was passed in the Legislature.
1.

Introduction: The District recognizes that the groundwater resources of the region are of vital importancenot only within the District but to areas outside the District. The District was created, in part, to conserve, preserve, protect,and prevent waste of all of the water resources within its jurisdiction. The District believes that the groundwater resourcesin the District can be managed in a prudent and cost effective manner through education and conservation, coupled withreasonable regulation, including permitting of new and existing non-exempt wells and registering of exempt wells.
Although the District has undertaken studies and has developed information about the occurrence and quality ofgroundwater in various geologic formations in and near the District, the District continues to conclude that one of thegreatest threats to prevent the District from achieving the stated mission are inadequate information about groundwater
occurrence, quality, groundwater production volumes, groundwater production rates, groundwater movement andgroundwater uses within and from aquifers regulated by the District based in part on a lack of knowledge about
groundwater production from exempt wells both within the District and groundwater occurrence and production from all
aquifers in areas without groundwater districts adjacent to or in close proximity with the area of Plum Creek Conservation
District. The District has concerns about the potential for groundwater quality degradation in some areas of the District
related to existing groundwater pumping and to old oil and gas activities. The District continually needs to develop more
information to understand how groundwater production, recharge, and flow into and out of the District are interrelated with2

production, recharge and flow in areas surrounding the District. Basic knowledge of the aquifers and their hydrogeologicalproperties, a quantification of resources, and development of data on groundwater quality are the foundation from which tobuild prudent planning measures. This Management Plan is intended as a tool to focus the thoughts and actions of thosegiven the responsibility for the execution of the District’s activities in developing information and in driving activities
implementing the District’s goals.
2.

Policy: It shall be the policy of the Board of Directors that the most beneficial use of groundwater in theDistrict is to maintain present non-wasteful groundwater uses of those in the District and then to provide for future
groundwater needs of citizens.

Groundwater shall be beneficially used, conserved, preserved, protected, and waste

prevented within the District to maintain the viability of those resources for current users and for users in the future who arein the District’s area. ,The Board of Directors, with the cooperation of the citizens of the District and of surrounding

political subdivisions, shall implement this management plan and any necessary modifications thereof to achieve this goal.
3. Governing Board: The District is governed by an appointed six member Board of Directors.
4. Daily Operations: The day-to-day management of District activities is carried out currently by a threemember staff led by Johnie Halliburton, Executive Manager and Daniel Meyer, Assistant Manager.
5.

Topography: The land surface of Caldwell County ranges from nearly flat to hilly. The minimum

elevation, about 295 feet, is at the southern tip of the County where Plum Creek joins the San Marcos River. The maximum
elevation in Caldwell County, about 725 feet, is in the area of the so-called “Iron Mountains” peaks, approximately 2.5
miles southeast of McMahan, a small community approximately 9 miles southeast of Lockhart. Regionally, the topographic
elevations increase from southeast to northwest.
The portion of District located in Hays County generally exhibits the same type of terrain, although the elevationdifferences are more pronounced. Some of the surface of the District’s area extends into Hays County, which overlies the
Balcones Escarpment, and provides drainage to a portion of Plum Creek.

3Plum Creek drains about 310 square miles, or about 60% of Caldwell County. In addition, a portion of Hays
County that is drained by Plum Creek is also in the boundaries of the District. There is a small area of Travis County thatdrains into Plum Creek but that area is not within the District’s boundaries.
6.

Location and Extent: The District is situated within parts of Caldwell and Hays Counties, but the District’s

boundaries are not conterminous with those of either Caldwell or Hays Counties. The original boundaries of the District aredescribed in Section 3 of the enabling statute that first created the District. In 2008 there were additional properties locatedin the southeastern portion of Caldwell County annexed into PCCD at the request of the landowners of the properties,
however; the area where those properties were located was also annexed into the Gonzales County Underground Water
Conservation District. S.B 1225 of the 82nd legislature enacted in 2011 was passed to and allowed the property owners
annexed by Plum Creek to choose which district they wanted to belong to with the result that the original boundaries of theDistrict were expanded by approximately 4672 acres. The most downstream point of the boundaries of the District is in themost southerly southeast corner of Caldwell County near the confluence of Plum Creek and the San Marcos River. The
calls in the original description of the boundaries of Plum Creek Conservation District are, generally, along tract or surveylines.
7.

Water Resources: The District does not hold, own or otherwise control any groundwater or surface waterrights. The District is located within the territory of the Guadalupe-Blanco River Authority (“GBRA”), which controls
substantial surface water rights associated with GBRA owned or operated facilities and reservoirs, including Canyon Lake.
Some water supply corporations providing retail water service within the District have access to surface water supplies
either through direct ownership, through lease, or through long term supply contracts. Most of the permitted surface waterrights in the vicinity of Plum Creek Conservation District are from the San Marcos River, which is not in the Boundaries of
the District. There are few surface water rights permits for diversions from Plum Creek and none known for diversion from
Plum Creek for any purpose other than agricultural use.
As a part of this Plan, each year the District will confer at least once with GBRA on cooperative opportunities forconjunctive resource management between ground and surface water suppliers to retail providers and other users.
4. GROUNDWATER RESOURCES

4

The PCCD has within its surface area boundaries the following geological formations: Quaternary Alluvium, Leona Gravel,
Austin-Pecan Gap, Navarro, Midway, Wilcox Group, Queen City, Reklaw, Saline Edwards, Trinity Group and the Carrizo
Sands. A geologic map of the area of the District is appended as Appendix C. The Texas Water Development Board
recently ran a groundwater availability model for the Southern portions of the Carrizo-Wilcox, Queen City, and Sparta,
aquifers within the District.

No information on discharges from, exchanges among aquifers, or flow into or out of the

Leona Gravel, or from recent alluvium deposits in the District is currently available from the Texas Water Development
Board. The full modeling report, GAM Run 12-001-Plum Creek Conservation District Management Plan, is appended tothis Plan as Appendix B.
5. MANAGEMENT ZONES

1. Alluvium – occurs along present day streams and rivers. Consists of sand, silt and clay. Serves as a limitedhousehold and livestock aquifer within the predominant sand facies.
2. Leona – occurs along scattered outcrops perpendicular to the Balcones Fault System and the IH-35
corridor. Serves as a shallow limited aquifer utilized manly as a small lot irrigation aquifer. Cotton andgrain farming has polluted much of the aquifer with nitrates, which are not recommended for human or
livestock consumption.
3. Weches – is primarily a glauconitic marine clay and is seldom utilized as stray sand or silt aquifer.
4. Queen City – occurs as a shallow limited sand and silt aquifer with lesser amounts of clay. The completed
wells are generally utilized for household and livestock.

5. Reklaw – primarily consists of clay with broken silt and sand intervals that can serve as shallow household
and livestock aquifers in limited areas.
6. Carrizo – occurs as a major irrigation and municipal aquifer. Consists of ancient barrier island loose finecoarse sand bodies separated by thin estuary silty clays. It is the major aquifer along the Upper Gulf Coastal
Plain across southern Texas capable of high production rates of fresh water.

7. Wilcox – often studied and associated with the overlying Carrizo aquifer. It is separated from the Carrizo
by a regional disconformity and exhibits some very different deltaic facies as compared to the Carrizo. It isutilized as a household, livestock and municipal source of fresh water over a wide area.
8. Midway – occurs primarily as a thick clay with minor amounts of silt near the top of the unit. It does not
generally serve as a reliable aquifer, even in limited silty zones.

59. Navarro – consists mainly as a thick sequence of expansive clay. It does not serve as an aquifer within theboundaries of the Plum Creek District.

10. Pecan Gap – this limestone and chalk unit does serve as a very limited household and livestock fractured
low yield aquifer along and parallel to the southeast side of the IH-35 corridor. Many of the wells
eventually go dry.
11. Austin Chalk – this very limited limestone and chalk aquifer immediately underlies the Pecan Gap andexhibits similar characteristics.

12. Eagle Ford – this unit is a petroliferous thin clay and does not serve as an aquifer.
13. Buda – occurs as a dense limestone unit in the PCCD area and does not serve as any known aquifer. It
does serve as an aquifer in the Uvalde County area.

14. Del Rio – does not serve as an aquifer in Texas. It occurs a weathered volcanic ash expansive clay.
15. Georgetown – occurs a dense limestone and is not expected to serve as a brackish or saline aquifer in the
PCCD area.

16. Edwards – this limestone and dolomite karst aquifer is the major fresh water source for the cities, towns
and industries along the IH-35 corridor which partially fall within the PCCD area. The unit is also a verystrong future candidate of brackish and saline water southeast of the IH-35 corridor that may eventually
rival the Carrizo aquifer.
17. Glen Rose – certain areas within the Glen Rose along the axis of the San Marcos Arch do harbor large
carbonate patch reefs that do contain substantial amounts of brackish and saline water. These Glen Rosepatch reefs will undoubtedly be utilized as desalination targets.

18. Bexar – occurs as a thin clay and does not serve as an aquifer.
19. James (Cow Creek) – does serve as a highly-used household and livestock aquifer along the northwestside of the IH-35 corridor in the Hill Country Balcones Fault System. Recently discovered higher yield
Cow Creek wells have been tested in a limited area of the Balcones Fault System.

20. Pine Island – occurs as natural gas charged expansive clay that does not serve as an aquifer.
21. Sligo – occurs as sandy glauconitic limestone that may serve as a future limited brackish and saline
aquifer.

622. Hosston – occurs as a sand and basal gravel aquifer, it serves most of the small town fresh water municipal
needs across the Texas Hill Country. The future desalination era will undoubtedly target the brackish andsaline portions of the Hosston clastics with the PCCD boundaries.

Management Zone Descriptive Table:

PeriodQuaternary

Epoch
Holocene
Pleistocene

Tertiary

Eocene/Paleocene

Upper

Cretaceous
Lower

Group/Formation/Member
Alluvium
Leona
WechesQueen City
Reklaw
Carrizo
Wilcox
MidwayNavarroPecan Gap
Austin Chalk
Eagle Ford
Buda
Del RioGeorgetown
Edwards
Glen Rose
Bexar
James (Cow Creek)
Pine Island (Hammett)
Sligo
HosstonDescription
Sand, silt, clay
Gravel, sand, silt, clay
Clay, silt, sandSand, clay
Clay, sand, silt
Sand, clay
Sand, clay. silt
Clay, silt, sandClay, silt, sand
Limestone, clay
Limestone, clay
Clay
Limestone
Clay
Limestone
Limestone, dolomite
Limestone, dolomite, clay
Clay
Limestone
Clay
Limestone, silt
Sand, clay

6. PRODUCTION AND SPACING OF WELLS
Production and spacing of all wells within the District is regulated by the District according to the Rules of the District. As
noted, the Rules may be changed from time to time. The District has recently revised its Rules, with the latest revision
becoming effective as of August 1, 2012, to take into account knowledge gained through its geologic studies that have beenongoing and to address anticipated increases in demands on the aquifers in and regulated by the District.

7.

MANAGEMENT OF GROUNDWATER SUPPLIES

7

The District evaluates and monitors groundwater availability, and regulates production consistent with the District Rules,
the GMAs(10 & 13) adopted Desired Future Conditions, (“DFC”) and the Modeled Available Groundwater determinationof the Texas Water Development Board. In consideration of the importance of groundwater availability to the economy andwelfare of those in the District, the District anticipates that in the future, groundwater production will be regulated asneeded to conserve groundwater, preserve groundwater availability, and protect permitted and exempt groundwater users, ina manner not to unnecessarily and adversely limit production or impact the economic viability of public and private
groundwater users. The District will identify and engage in such activities and practices that will permit groundwaterproduction and, as appropriate, will protect the aquifer and groundwater availability by restricting future requested pumping
quantities, if necessary, according to the best information then available to the District.
Currently there are a number of monitoring wells that are in PCCD’s Aquifer Water Level Observation Program that are
being used in order to monitor aquifer conditions within the district and to track compliance with the DFCs. On an annual
basis, in accord with advice from its technical consultant, PCCD will, if necessary, modify the program. The District will
make a regular assessment of water supply and groundwater storage conditions as observed in data from its network andwill report those conditions to the Board and to the public. The District will undertake investigations, and co-operate withthird-party investigations including neighboring districts, of the groundwater resources within the District, and the results of
the investigations will be made available to the public upon being presented at a meeting of the Board. The District will
manage the available groundwater based on the “Desired Future Conditions” and Modeled Available Groundwater
determination of the aquifers.
The District has adopted Rules to regulate groundwater withdrawals by means of well spacing and production limits or,alternatively, in accord with a study of the effects of the proposed well on the targeted aquifer. The District may deny awater well production permit or limit groundwater withdrawals in accordance with the Rules of the District. In making adetermination to deny a permit or limit groundwater withdrawals, the District will consider the available data and evidence
and then weigh the public benefit against the individual needs and hardship in accord with State law.
The relevant factors to be considered in a determination to grant or deny a well or a production permit or limit groundwater
withdrawals are stated in the District's Rules and information furnished can include:81. Whether the application contains all the information required to be submitted to the District pursuant to these Rules;
2. Whether the application is in conformance with any applicable requirements under Rule 20 – Classification, Spacing
and Production Provisions established by the District;

3. Whether the proposed use of groundwater unreasonably affects existing groundwater or surface water resources;
4. Whether the proposed use of groundwater is a beneficial use consistent with District’s Certified Groundwater
Management Plan;

5. Whether the applicant has agreed to avoid waste and achieve water conservation;
6. Whether the proposed use of the groundwater will result in subsidence;
7. Whether the applicant has agreed that reasonable diligence will be used to protect groundwater quality, and that theapplicant will follow well plugging guidelines at the time of well closure;

8. The equitable distribution of the resource; and9. The potential effect the permit may have on the aquifer, sustainability of the recharge on the aquifer as a whole, andpotential impacts to prior existing permitted groundwater users and exempt groundwater users.

10. The modeled available groundwater determined by the executive administrator;
11. The executive administrator's estimate of the current and projected amount of groundwater produced under
exemptions granted by district rules and Section 36.117;

12. The amount of groundwater authorized under permits previously issued by the district
13. A reasonable estimate of the amount of groundwater that is actually produced under permits issued by the district;
14. Yearly precipitation and production patterns.
15. Estimated Average Annual Recharge

9The transport of groundwater out of the District is regulated by the District according to the Rules of the District.
In pursuit of the District's mission of protecting the resource to facilitate its maximum beneficial use, the District may
require reduction of permitted groundwater withdrawals to amounts that, based on then available current information, will
not knowingly cause permanent harm to an aquifer. To achieve this purpose, the District may, at the Board's discretion andafter notice and hearing, amend or revoke any permit for non-compliance, or reduce the production authorized by permit
based upon reliable scientific data for the purpose of protecting the aquifer and groundwater availability. The determination
to seek the amendment of a permit will be based on aquifer conditions observed by the District confirmed by reliable
scientific analysis. The determination to seek revocation of a permit will be based on compliance and non-compliance with
the District's Rules and regulations, and reliable scientific evidence. The District will enforce the terms and conditions ofpermits and the Rules of the District, as necessary, by fine and/or enjoining the permit holder, or non-permit holder, in acourt of competent jurisdiction as provided for in Chapter 36, Texas Water Code.
A drought management plan has been adopted by the Board to cope with the effects of water supply deficits due to climaticor other conditions. In its annual review of the drought management plan, the District, in establishing drought triggers
and stages, anticipates consideration of the economic effect of conservation measures upon all water resource user groups,
the local implications of the degree and effect of changes in water storage conditions, the unique hydrogeological conditionsof the aquifers within the District and the appropriate conditions under which to implement the drought management plan.
The District will employ reasonable and necessary technical resources at its disposal to evaluate the groundwater resources
available within the District and to determine the effectiveness of regulatory or conservation measures. The District
anticipates that its drought management plan will provide that a public or private user may appeal to the Board fordiscretion in enforcement of the provisions of the water supply deficit drought management plan on grounds of adverse
economic hardship or unique local conditions. The exercise of discretion by the Board, shall not be construed as limiting thepower of the Board.

10

8.

ACTIONS, PROCEDURES, PERFORMANCE AND PLAN IMPLEMENTATIONThe District will implement the provisions of this Plan and will utilize the provisions of this Plan as a guidepost for ongoing evaluation determining the direction or priority for all District activities. All operations of the District, all agreements
entered into by the District and any additional planning efforts in which the District may participate will be consistent withthe provisions of this Plan.
The District has adopted Rules relating to the permitting of wells, production and transport of groundwater. The Rules
adopted by the District will be modified to take into account this Plan once it has been approved and shall be amended asnecessary, pursuant to Chapter 36 of the TEXAS WATER CODE consistent with the provisions of this Plan based uponreliable scientific evidence. All Rules will be enforced. The promulgation and enforcement of the Rules will be based on thebest technical data reasonably available. A link to the District rules is provides as follows:

http://www.pccd.org/PCCD%20GW%20Management%20&%20Protection%20Rules.pdf

The District shall treat all citizens equally. Citizens may apply to the District for a variance in enforcement of the Rules ongrounds of adverse economic effect or unique local conditions. In granting a variance to any rule, the Board shall consider
the potential for adverse effect on adjacent landowners and the rights of other groundwater owners and users within theDistrict. The exercise of said discretion by the Board, shall not be construed as limiting the power of the Board.
The District will seek cooperation with other agencies in the implementation of this Plan and the management ofgroundwater supplies within the District.
The District believes that there is a significant issue that affects groundwater within its boundaries and affects the District’s
ability to effectively manage the groundwater resources within the District. That issue is that there are very productive
regions of aquifers that are near but not within Plum Creek Conservation District’s regulatory authority. Should there belarge volume water production from aquifers in these areas, there is significant potential that such production will impact
water quantity and/or water quality of users in the District.
The fact that Plum Creek Conservation District's surface boundaries also includes areas that are within the Barton Springs
Edwards Aquifer Conservation District and the Edwards Aquifer Authority [the District does have authority over any

11aquifers in Hays and Caldwell County within its boundary that are not regulated by either the Edwards Aquifer Authority or
the Barton Springs-Edwards Aquifer Conservation District -] indicates that Plum Creek should cooperate with [and provide
some assistance to] the EAA and the Barton Springs-Edwards District while developing plans for understanding and use ofwater resources to the fast growing area along Interstate 35 between San Antonio and Austin. PCCD's territory extends
from Northwest of IH 35 to IH 10 and encompasses much of an area that is projected to have rapid growth. The completionof SH 130, along with other regional projects is considered by many to be a necessary infrastructure component to allow for
population and economic growth. Developers and retail water suppliers are already searching for additional water supplies
to meet growing demand.
Finally, there are significant long-existing oil and gas operations in the southern part of the District along with the possible
future exploration and development of gas-liquids shale plays. Should those activities continue to increase as the price foroil and gas resources stays high, there may be significant consumption of water, or other groundwater impacts such as thepotential for pollution, related to such activities that is outside the scope of regulatory power of any groundwater district.
For these reasons, all activities of the District will be undertaken in co-operation and coordinated with the appropriate state,regional or local water management entities where they are present. However, simply stated, in Hays County there are manysuch agencies looking at management of groundwater; in Caldwell County the absence of a groundwater agency in theeastern and western part of the county makes management of the groundwater resources in the District more challenging.
9. METHODOLOGY FOR TRACKING DISTRICT PROGRESS IN ACHIEVING MANAGEMENT GOALSThe Groundwater Manager of the District will prepare and present an annual report to the Board of Directors on theperformance of the District with respect to achieving its management goals and objectives. The presentation of the reportwill occur during the last monthly Board meeting each fiscal year, beginning after the adoption and approval of this Plan.
The report will include an enumeration and listing of activities furthering the District’s management objectives during the
fiscal year. Each activity will be referenced to the estimated expenditure of staff time and District resources used inaccomplishment of the activity. The notations of activity frequency, staff time and resources used will be referenced to theappropriate performance standard for each management objective describing the activity, so that the effectiveness andefficiency of the District’s operations may be evaluated. The Board will maintain the adopted report on file, for public

12inspection, at the District's offices. This methodology will apply to all management goals contained within this plan.
10.

MANAGEMENT GOALS, OBJECTIVES, & PERFORMANCE STANDARDS

10.1 Providing the Most Efficient Use of Groundwater
Management Objectives:
1. The PCCD Aquifer Water Level Observation Well Program will have at least 6 observation wells located according
to management zones within the District, and measure those wells at least one time a year.
2. As part of the Aquifer Water Level Observation Program, the District will geographically divide the surface area
overlying the aquifers of Plum Creek Conservation District into a grid-type network of units.
3. The district will have a goal of establishing at least one monitoring water well in each of these units.
4. The District will provide educational leadership to citizens within the District concerning this subject. The activity
will be accomplished annually through at least one printed publication, such as a brochure, and public speaking atservice organizations and public schools as provided for in the District's Public Education Program.
5. The District will use its best efforts to obtain information on water being produced from areas in Caldwell County
that are outside the boundaries of the District.
6. The District will use its best efforts to obtain information on groundwater being produced from groundwateraquifers in counties surrounding the District as well as in areas close to the District that are not in a groundwater
conservation district in order to develop information about impacts of such production on groundwater in theDistrict.
Performance Standards:
1.

The PCCD Aquifer Water Level Observation Well Program will have at least 6 observation wells locatedaccording to management zones within the District.

2. Water levels at these observation wells will be measured a minimum of one time during the year.

13

3. As part of the Aquifer Water Level Observation Program the District will geographically divide the surface area
overlying the aquifers of Plum Creek Conservation District into a grid type network of units within one year of the
adoption of this plan.
4. On an annual basis the district will assess the District’s progress of establishing at least one monitoring well in eachof these units.
5. PCCD representatives will circulate at least one publication and participate in one speaking engagement each year.
6. PCCD representatives will attend and participate in GMA meetings appropriate to the District’s regulatory
authority.
7. PCCD will periodically seek information from nearby groundwater districts not in the same GMA but drawing fromthe same aquifers regulated by the District.
10.2 Controlling and Preventing Waste of Groundwater.
Management Objective:
The District will provide educational leadership to citizens within the District concerning this subject. The activity
will be accomplished annually through at least one printed publication, such as a brochure.
Performance Standard:
1. Each calendar year Representatives of Plum Creek will prepare at least one informational article listing current
data related to groundwater production and well levels. The goal of the article is to make those who use anddepend on the groundwater aware of their use, aware of the impacts of their use, and the need to be responsible
in that use.
2.

At its offices Plum Creek will maintain an inventory of publications of others, such as those prepared by the
Guadalupe Blanco River Authority about the necessity for conservation, and serve as a local source for
distribution of those publications.

10.3 Controlling and Preventing Subsidence14

It is uncertain as to whether subsidence from the production of groundwater would likely occur in the Plum Creek
Conservation District. The District historically has not, as we know, experienced any subsidence from any cause.
Accordingly, the District’s Plan does not contain any “Management Objective” or related “Performance Standards” toaddress the issue of non-existent subsidence. The TWDB has commissioned a subsidence study for the Major andMinor aquifers of Texas. If after reviewing TWDB’s report, it shows scientific evidence of subsidence or the potential
there of in PCCD, then the District would further investigate the possibility of whether there would be landowners
negatively impacted. Alluvium is poorly consolidated, but generally too thin to experience measurable (if any)
subsidence due to groundwater withdrawals.
10.4 Addressing Conjunctive Surface Water Management Issues
Management Objective:
Each year the District will seek conferral with the Guadalupe-Blanco River Authority (GBRA) and/or otherlocal political subdivisions and water and wastewater utilities on cooperative opportunities for conjunctive
resource management.
Performance Standard:
1. Each year the District will seek conferral with the GBRA, other political subdivisions or water and wastewater
utilities providing retail water service within Plum Creek’s boundaries, to gain information about conjunctive
resource management.
2. The District will continue to participate in the quarterly meetings of the Plum Creek Watershed Project through thetime of completion of the water quality management plan being developed in that effort
10.5 Addressing Drought Conditions
Management Objective:
Review the Drought Management Strategy Plan annually, and revise it if necessary based upon the availabilityof additional scientific data collected by or presented to the Board . The Drought Management Strategy Plan
will be implemented when specified conditions require.

15Performance Standards:

1. Review on an annual basis all of the conditions and requirements specified in the Drought Management Strategy
Plan that would trigger its implementation.
2. Use data that are available from local weather stations monitoring rainfall, looking at the correlation between
rainfall, water levels, groundwater recharge and availability.
3. Provide a link on the District’s website for TWDB’s drought web page. https://waterdatafortexas.org/drought
10.6 Addressing Natural Resource Issues That Impact the Use and Availability of Groundwater and Which are
Impacted By the Use of Groundwater
Management Objectives:
1. Each year the District will seek conferral with a representative of the Texas Railroad Commission (RRC) on theimpact of oil and gas production or waste and disposal operations associated with oil and gas production on
groundwater availability and quality, as well as the impact of groundwater production on the production of oil andgas in the District.
2. Also, during each year the District will evaluate all permit applications for new production injection or disposal
wells permitted by the Railroad Commission, if any are filed, and the information submitted by the applicants on
those wells prior to drilling, in order to assess the impact of these wells on the groundwater resources in the District.
Performance Standards:
1. Will seek conferral annually with a representative of the Texas RRC ;2. The addition of available RRC well data to the District’s database;
3. Report
permittotheapplications

PCCD
are

filed,

Board
and

of
the

Directors
possiblegroundwater resources in the District; and16

impacts

when

new

of

those

groundwater
new

wells

well
on

the

4. Annual reports to the Board about consumption and use of groundwater for commercial purposes, including
irrigation uses and enhanced oil and gas production when information is available.
10.7 Addressing Conservation, Recharge Enhancement, Rainwater Harvesting,
Precipitation Enhancement, or Brush Control where appropriate and cost-effective
Management Objectives:
1. The District will provide educational leadership and encouragement to citizens within the District on the need
for water conservation and publicize the benefits of rainwater harvesting and brush control. The educational
efforts and publicity will be through distribution of brochures produced either by the District or by others andmade available by the District and through the presentation annually of informational articles that tabulate data
developed by the District on the groundwater resources being monitored. Each of the following topics will be
addressed in the publications:A. Conservation
B. Rainwater Harvesting
C. Brush Control

2. With respect to recharge enhancement, the District will continue to develop geologic data to map and gain
understanding of the relationship between recharge to and discharge from various formations to each other andto Plum Creek as it flows through the District. At this time, the relationships among the aquifers and the Creek
are not well documented or understood. It is known that recharge of much of the groundwater that can be foundin the District, and in areas next to the District that are not in any groundwater district, originate outside theboundaries of the District. There is some natural recharge to aquifers in the District from both streams andfrom areas where those aquifers are at the surface. However, the formations found in the District are not readilysusceptible to recharge enhancement.
3. The District has an active brush control program for the flood water retention structures that it maintains. The

17

District also cooperates with the US Department of Agriculture in agricultural conservation efforts and actively
supports the local Soil and Water Conservation District.
4. The District has participated in the funding of a rainwater harvesting demonstration project at the LulingFoundation and will continue to monitor the results of that project and report those results in its articles.
5. The District does not believe that precipitation enhancement is appropriate and cost effective in its area. At thesame time, PCCD is aware of efforts being implemented by other districts and will continue to monitor the
information gathered from those and determine whether such efforts might be attempted by the District. The
District will continue to assess the need and opportunity for precipitation enhancement in the District at least
once every five years.
Performance Standards:
1. Preparation and distribution of at least two publications each year containing information about conservation,
rainwater harvesting and brush control efforts.
2. The District staff will continue to cooperate with the Natural Resource Conservation Service to control brush on
the 28 flood water retention structures maintained by the District. In addition, the District will participate in atleast one meeting each year with the local soil and water conservation district to discuss brush control efforts,
and will continue to support the local soil and water conservation districts efforts through and annual financial
contribution.
3. The District will obtain, if available, at least one report each year about the relationship between recharge ofaquifers in the District and rainfall on the surface to determine whether it would be appropriate and costeffective to develop a trial plan for recharge enhancement.
4. At least once every 5 years the staff will report to the Board on the results of nearby precipitation enhancement
activities so the Board can consider the feasibility of participating in any efforts in the area of lands that areserving as sources of recharge for groundwater found in the District. If the Board determines that precipitation
enhancement might be appropriate and cost effective, within two years the Board will develop and adopt a18

program allowing participation in precipitation efforts ongoing in the region.

10.8. Mitigation & Desired Future Conditions of Groundwater Resources

The mitigation plan will be reviewed on an annual basis and revised if necessary in order to be compliant with the
adopted DFCs and any current or new state law in effect. Further, any projects that have been mitigated will also be
reviewed on an annual basis.
Review of groundwater resources in the District in comparison with the Desired Future Conditions of thoseresources and preparation of a recommendation for any mitigation actions within six (6) months or later if
warranted.
10.9 Addressing the Desired Future Conditions established under TWC §36.108
Management Objective:
At least once every three years, the District will monitor water levels and evaluate whether the change in waterlevels is in conformance with the DFCs adopted by the District. The District will estimate total annual groundwaterproduction for each aquifer based on the water use reports, estimated exempted use, and other relevant information,and compare these production estimates to the MAGs.
Performance Standard:
1. At least once every three years, the executive manager will report to the Board the measured water levels
obtained from the monitoring wells within each Management Zone, the average measured drawdown for eachManagement Zone calculated from the measured water levels of the monitoring wells within the Management
Zone, a comparison of the average measured drawdowns for each Management Zone with the DFCs for eachManagement Zone, and the District’s progress in conforming with the DFCs.
2. At least once every three years, the executive manager will report to the Board the total permitted production andthe estimated total annual production for each aquifer and compare these amounts to the MAGs for each aquifer.

4. In conjunction with information from PCCD’s drought management plan, Aquifer Water Level Observation Well
Program , water use production patterns, analysis from PCCD’s geological consultant and other pertinent technicaldata, the board, at least once every three(3) years will determine if conditions are present that would jeopardize

19

DFC compliance and if so, schedule a hearing to address limiting water use for water well production permit
holders.
10.10

Alternative Supply

Management Objective:
1. The District will assess the need and feasibility, including funding options, of developing a program to research,
participate in regional studies with other groundwater conservation districts and regional agencies in order to look at
the potential benefits of alternative water supply sources such as underdeveloped aquifers, one being the Trinity
Aquifer, desalinization, rainwater harvesting, and aquifer recovery and storage in and around our district.

Performance Standard:
1. Assess the groundwater resources of the Trinity Group and saline Edwards. The district will assess the need todevelop one or more monitoring wells in order to determine the aquifer characteristics and potential for public
supply and to cooperate with GCDs that have similar goals.
2. The district will evaluate and support studies on ASR and on desalination projects through cooperative
collaboration or financial assistance.
11.

PROJECTED WATER DEMANDS WITHIN THE DISTRICT
Please refer to Appendix A-Estimated Historical Groundwater Use and 2017 State Water Plan Datasets

12.

PROJECTED SURFACE WATER SUPPLIES WITHIN THE DISTRICT
Please refer to Appendix A-Estimated Historical Groundwater Use and 2017 State Water Plan Datasets

13. WATER NEEDS WITHIN THE DISTRICT
Please refer to Appendix A-Estimated Historical Groundwater Use and 2017 State Water Plan Datasets

20

14. WATER MANAGEMENT STRATEGIES WITHIN THE DISTRICT
Please refer to Appendix A-Estimated Historical Groundwater Use and 2017 State Water Plan Datasets

15. ESTIMATE OF GROUNDWATER USE IN THE DISTRICT
Please refer to Appendix A-Estimated Historical Groundwater Use and 2017 State Water Plan Datasets
16. Annual Amount of Recharge From Precipitation to the Groundwater Resources within the District

Please refer to Appendix B-GAM Run 12-001: Plum Creek Conservation District Management Plan.
17. Annual Volume of Water that Discharges from the Aquifer to Springs and Surface Water
BodiesPlease refer to Appendix B-GAM Run 12-001: Plum Creek Conservation District Management Plan.
18. Estimate of the Annual Volume of Flow into the District, out of the District, and Between
Aquifers in the District
Please refer to Appendix B-GAM Run 12-001: Plum Creek Conservation District Management Plan.

19. Estimate of Modeled Available Groundwater in District Based on Desired Future Conditions
Texas Water Code § 36.001 defines modeled available groundwater as “the amount of waterthat the executive administrator determines may be produced on an average annual basis toachieve a desired future condition established under Section 36.108”.
The joint planning process set forth in Texas Water Code § 36.108 must be collectively
conducted by all groundwater conservation districts within the same GMA. The District is amember of GMA 10 & 13. GMA 10 and GMA 13 adopted DFCs, as summarized below, and then forwarded
them to the TWDB for MAG development which are also shown below.
TABLE 1: Desired Future Conditions for GMA 10 & 13
21

GMA

10

10

13

Aquifers

Trinity Group

Saline Edwards

Carrizo-Wilcox,
Etal

Adopted DFC
Trinity
Aquifer,inthehydrologicallyconfinedzone
downdip of the Trinity outcrop:
Outside of Uvalde and Bexar
Counties: Average regional well
drawdown not exceeding 25 feetduringaveragerecharge
conditions (including exempt andnon-exempt use)

Saline Edwards Aquifer in the
Northern GMA Subdivision:
No more than 75 feet of regional
average potentiometric surface
drawdown due to pumping whencompared to pre-development
conditions

The first proposed desired future
condition for the Carrizo-Wilcox,
Queen City and Sparta aquifers in
Groundwater Management Area 13
is that 75 percent of the saturated
thickness in the outcrop at the endof 2012 remains in 2070. This
desired future condition isconsidered feasible despite model
predictions to the contrary as
detailed in GMA 13 Technical
Memorandum 16-08”,

And
In addition, a secondary proposed
desired future condition for the
Carrizo-Wilcox, Queen City, andSparta aquifers in Groundwater
Management Area 13 is an averagedrawdown of 48 feet for all of GMA
13. The drawdown is calculated
from the end of 2012 conditions to

22

Adoption Date

June 26, 2017

June 26, 2017

November 21, 2016

the year 2070. This desired future
condition is consistent with
Scenario 9 as detailed in GMA 13
Technical Memorandum 16-01 and
GMA 13 Technical Memorandum
16-08

TABLE 2: Summary of Modeled Available Groundwater for the Plum Creek Conservation District (complete setof values is available in the appendix)

GMA

Aquifers

MAG (acre-ft/ per year)

TWDB MAG Report

10

Trinity Group276

GAM Run 16-033 MAG:

10

Saline Edwards

812

GAM Run 16-033 MAG:

13

Carrizo-Wilcox

Year 2012 = 21,073

GAM Run 17-027 MAG

Year 2070 = 19,625

13

Carrizo

13

Wilcox Group

13(Upper, Middle & Lower)

6057

GAM Run 17-027 MAG

Year 2012 = 15,015
GAM Run 17-027 MAG
Year 2070 = 13,567

Queen City

22

20. GEOLOGY MAP OF PCCD
Please refer to Appendix C.

23

GAM Run 17-027 MAG

We the undersigned members of the Board of Directors do hereby certify and confirm the adoption of this revised andamended Groundwater Management Plan of the Plum Creek Conservation District on this the 13th day of November, 2007
as evidenced by our signatures below:

Board of Directors___________________________________
James A. Holt, Jr., President___________________________________
James O. Lipscomb, Vice President___________________________________
Lucy Knight, Director___________________________________
Peter Reinecke, Director___________________________________
Ben Twidwell, Director___________________________________
Fred Rothert, Director
Attested by: _______________________________
Johnie Halliburton, Executive Manager

24

Estimated Historical Groundwater Use
And 2017 State Water Plan Datasets:
Plum Creek Conservation Districtby Stephen Allen
Texas Water Development Board
Groundwater Division
Groundwater Technical Assistance Section
stephen.allen@twdb.texas.gov(512) 463-7317
September 20, 2017

GROUNDWATER MANAGEMENT PLAN DATA:This package of water data reports (part 1 of a 2-part package of information) is being provided to
groundwater conservation districts to help them meet the requirements for approval of their fiveyear groundwater management plan. Each report in the package addresses a specific numberedrequirement in the Texas Water Development Board's groundwater management plan checklist. The
checklist can be viewed and downloaded from this web address:
http://www.twdb.texas.gov/groundwater/docs/GCD/GMPChecklist0113.pdf
The five reports included in this part are:
1. Estimated Historical Groundwater Use (checklist item 2)

from the TWDB Historical Water Use Survey (WUS)
2. Projected Surface Water Supplies (checklist item 6)
3. Projected Water Demands (checklist item 7)
4. Projected Water Supply Needs (checklist item 8)
5. Projected Water Management Strategies (checklist item 9)from the 2017 Texas State Water Plan (SWP)
Part 2 of the 2-part package is the groundwater availability model (GAM) report for the District(checklist items 3 through 5). The District should have received, or will receive, this report from the
Groundwater Availability Modeling Section. Questions about the GAM can be directed to Dr. Shirley
Wade, shirley.wade@twdb.texas.gov, (512) 936-0883.

25

DISCLAIMER:
The data presented in this report represents the most up-to-date WUS and 2017 SWP data available
as of 9/20/2017. Although it does not happen frequently, either of these datasets are subject tochange pending the availability of more accurate WUS data or an amendment to the 2017 SWP.
District personnel must review these datasets and correct any discrepancies in order to ensure
approval of their groundwater management plan.
The WUS dataset can be verified at this web address:

http://www.twdb.texas.gov/waterplanning/waterusesurvey/estimates/
The 2017 SWP dataset can be verified by contacting Sabrina Anderson(sabrina.anderson@twdb.texas.gov or 512-936-0886).
The values presented in the data tables of this report are county-based. In cases where
groundwater conservation districts cover only a portion of one or more counties the data values are
modified with an apportioning multiplier to create new values that more accurately represent
conditions within district boundaries. The multiplier used in the following formula is a land area
ratio: (data value * (land area of district in county / land area of county)). For two of the four SWP
tables (Projected Surface Water Supplies and Projected Water Demands) only the county-wide wateruser group (WUG) data values (county other, manufacturing, steam electric power, irrigation, mining
and livestock) are modified using the multiplier. WUG values for municipalities, water supply
corporations, and utility districts are not apportioned; instead, their full values are retained when
they are located within the district, and eliminated when they are located outside (we ask each
district to identify these entity locations).
The remaining SWP tables (Projected Water Supply Needs and Projected Water Management
Strategies) are not modified because district-specific values are not statutorily required. Each districtneeds only “consider” the county values in these tables.
In the WUS table every category of water use (including municipal) is apportioned. Staff determinedthat breaking down the annual municipal values into individual WUGs was too complex.
TWDB recognizes that the apportioning formula used is not perfect but it is the best available
process with respect to time and staffing constraints. If a district believes it has data that is moreaccurate it can add those data to the plan with an explanation of how the data were derived.
Apportioning percentages that the TWDB used are listed above each applicable table.
For additional questions regarding this data, please contact Stephen Allen(stephen.allen@twdb.texas.gov or 512-463-7317).

Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

Estimated Historical Water Use
TWDB Historical Water Use Survey (WUS) Data
Groundwater and surface water historical use estimates are currently unavailable for calendar year
2016. TWDB staff anticipates the calculation and posting of these estimates at a later date.

CALDWELL COUNTY

51.56% (multiplier)Year

Source

2015

GW

933

0

SW

1,511

4

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

Municipal

Manufacturing

Mining

All values are in acre-feet

Steam Electric

Irrigation

Livestock

Total

0

0

207

82

1,222

0

0

27

326

1,868

GW

1,053

0

1

0

335

81

1,470

SW

1,521

3

0

0

30

322

1,876

GW

1,046

0

0

0

297

77

1,420

SW

1,509

2

0

0

20

306

1,837

GW

1,207

0

0

0

390

77

1,674

SW

1,615

0

0

0

42

305

1,962

GW

1,546

0

13

0

527

86

2,172

SW

1,624

0

27

0

41

344

2,036

GW

1,357

1

2

0

368

87

1,815

SW

1,580

0

3

0

19

349

1,951

GW

1,400

1

0

0

76

85

1,562

SW

1,486

0

0

0

9

338

1,833

GW

1,278

1

0

0

134

91

1,504

SW

1,617

0

0

0

589

360

2,566

GW

914

1

0

0

32

107

1,054

SW

1,593

0

0

0

606

427

2,626

GW

1,038

1

0

0

179

99

1,317

SW

1,393

0

0

0

0

396

1,789

GW

1,131

1

0

0

155

140

1,427

SW

1,257

0

0

0

13

558

1,828

GW

1,922

1

0

0

82

39

2,044

SW

704

0

0

0

12

503

1,219

GW

1,994

1

0

0

66

36

2,097

SW

671

0

0

0

483

462

1,616

GW

2,014

3

0

0

115

36

2,168

SW

557

0

0

0

705

458

1,720

GW

1,999

4

0

0

115

33

2,151

SW

622

0

0

0

705

425

1,752

GW

2,043

5

0

0

71

47

2,166

SW

560

0

0

0

439

426

1,425

Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

HAYS COUNTY
Year

Source

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

All values are in acre-feet

9.11% (multiplier)
Municipal

Manufacturing

Mining

GW

797

16

27

0

23

8

871

SW

1,260

0

0

145

17

272

1,694

GW

821

17

34

69

57

7

1,005

SW

1,208

0

0

0

0

293

1,501

GW

1,073

16

34

91

42

7

1,263

SW

1,193

0

0

0

0

254

1,447

GW

1,184

18

45

0

60

6

1,313

SW

1,214

0

0

0

8

223

1,445

GW

1,267

16

59

0

80

9

1,431

SW

1,221

0

30

0

1

213

1,465

GW

1,179

14

61

0

60

9

1,323

SW

797

0

32

0

1

249

1,079

GW

1,096

14

60

0

67

28

1,265

SW

797

0

31

0

0

260

1,088

GW

1,103

16

59

0

65

28

1,271

SW

724

0

30

0

2

581

1,337

GW

941

13

31

0

112

29

1,126

SW

635

1

1

0

18

353

1,008

GW

1,120

17

32

0

22

28

1,219

SW

581

0

0

0

0

313

894

GW

965

16

32

0

13

26

1,052

SW

481

0

0

0

3

309

793

GW

938

14

32

0

11

18

1,013

SW

437

1

0

0

29

384

851

GW

949

14

51

0

9

18

1,041

SW

560

0

0

0

23

217

800

GW

936

14

67

0

1

21

1,039

SW

456

0

0

0

19

219

694

GW

952

19

56

0

1

19

1,047

SW

413

0

0

0

19

335

767

GW

908

22

40

0

1

16

987

SW

414

0

0

0

15

330

759

Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

Steam Electric

Irrigation

LivestockTotal

Projected Surface Water Supplies
TWDB 2017 State Water Plan Data

51.56% (multiplier)

CALDWELL COUNTY

All values are in acre-feet

RWPG

WUG

WUG Basin

Source Name

2020

2030

2040

2050

2060

2070

L

COUNTY LINE WSC

GUADALUPECANYON
LAKE/RESERVOIR

103

83

61

39

18

0

L

COUNTY-OTHER,CALDWELLGUADALUPEGUADALUPE RUNOF-RIVER

258

258

258

258

258

258

L

GONZALES COUNTYWSCGUADALUPECANYON
LAKE/RESERVOIR

19

21

22

23

25

25

L

LIVESTOCK, CALDWELL COLORADOCOLORADOLIVESTOCK LOCALSUPPLY

15

15

15

15

15

15

L

LIVESTOCK, CALDWELL GUADALUPEGUADALUPELIVESTOCK LOCALSUPPLY

243

243

243

243

243

243

L

MARTINDALE

GUADALUPECANYON
LAKE/RESERVOIR

90

90

90

90

90

90

L

MARTINDALE

GUADALUPEGUADALUPE RUNOF-RIVER

100

100

100

100

100

100

L

MAXWELL WSC

GUADALUPECANYON
LAKE/RESERVOIR

359

368

373

375

376

376

L

MAXWELL WSC

GUADALUPEGUADALUPE RUNOF-RIVER

543

557

565

568

569

569

L

SAN MARCOSGUADALUPECANYON
LAKE/RESERVOIR

2

2

2

3

3

3

L

UHLANDGUADALUPECANYON
LAKE/RESERVOIR

79

94

110

126

142

158

1,811

1,831

1,839

1,840

1,839

1,837

Sum of Projected Surface Water Supplies (acre-feet)

9.11% (multiplier)

HAYS COUNTY
RWPG

WUG

WUG Basin

Source NameK

AUSTINCOLORADOCOLORADO RUN-OFRIVER

K

BUDA

COLORADOK

All values are in acre-feet

2020

2030

2040

2050

2060

2070

13

127

249

631

1,519

2,749

CANYON
LAKE/RESERVOIR

1,381

1,292

1,181

1,041

882

701

COUNTY-OTHER, HAYS COLORADOHIGHLAND LAKES
LAKE/RESERVOIRSYSTEM

128

128

128

128

128

128

K

DRIPPING SPRINGSCOLORADOHIGHLAND LAKES
LAKE/RESERVOIRSYSTEM

506

506

506

506

506

506

K

DRIPPING SPRINGSWSC

COLORADOHIGHLAND LAKES
LAKE/RESERVOIRSYSTEM

133

280

461

691

953

1,126

K

LIVESTOCK, HAYSCOLORADOCOLORADOLIVESTOCK LOCALSUPPLY

17

17

17

17

17

17

K

WEST TRAVIS COUNTY COLORADOHIGHLAND LAKES

4,521

4,521

4,521

4,521

4,521

4,521

Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

PUBLIC UTILITY
AGENCY

LAKE/RESERVOIRSYSTEML

BUDA

GUADALUPECANYON
LAKE/RESERVOIR

299

388

499

639

798

979

L

COUNTY LINE WSC

GUADALUPECANYON
LAKE/RESERVOIR

226

197

161

113

57

0

L

COUNTY-OTHER, HAYS GUADALUPECANYON
LAKE/RESERVOIR

353

353

353

353

353

353

L

CRYSTAL CLEAR WSC

GUADALUPECANYON
LAKE/RESERVOIR

323

317

319

329

340

354

L

GOFORTH SUDGUADALUPECANYON
LAKE/RESERVOIR

1,050

1,050

1,050

1,050

1,050

1,050

L

IRRIGATION, HAYSGUADALUPEGUADALUPE RUNOF-RIVER

12

12

12

12

12

12

L

KYLE

GUADALUPECANYON
LAKE/RESERVOIR

5,743

5,743

5,743

5,743

5,743

5,732

L

LIVESTOCK, HAYSGUADALUPEGUADALUPELIVESTOCK LOCALSUPPLY

19

19

19

19

19

19

L

MAXWELL WSC

GUADALUPECANYON
LAKE/RESERVOIR

101

92

87

85

84

84

L

MAXWELL WSC

GUADALUPEGUADALUPE RUNOF-RIVER

153

139

131

128

127

127

L

SAN MARCOSGUADALUPECANYON
LAKE/RESERVOIR

9,998

9,998

9,998

9,997

9,997

9,997

L

STEAM ELECTRIC
POWER, HAYSGUADALUPECANYON
LAKE/RESERVOIR

224

224

224

224

224

224

L

UHLANDGUADALUPECANYON
LAKE/RESERVOIR

99

133

175

229

290

360

25,29925,53625,83426,456

27,62029,039Sum of Projected Surface Water Supplies (acre-feet)

Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

Projected Water Demands
TWDB 2017 State Water Plan Data
Please note that the demand numbers presented here include the plumbing code savings found in the
Regional and State Water Plans.

51.56% (multiplier)

CALDWELL COUNTY

All values are in acre-feet

RWPG

WUG

WUG Basin

2020

2030

2040

2050

2060

2070

L

AQUA WSC

COLORADO

43

51

60

68

77

86

L

AQUA WSCGUADALUPE

242

289

336

385

435

484

L

COUNTY LINE WSC

GUADALUPE

82

97

114

132

149

166

L

COUNTY-OTHER, CALDWELL

COLORADO

26

31

36

41

46

52

L

COUNTY-OTHER, CALDWELLGUADALUPE

348

410

474

541

612

681

L

CREEDMOOR-MAHA WSC

COLORADO

114

133

152

172

195

216

34

39

45

50

56

L

CREEDMOOR-MAHA WSC

GUADALUPE

29

L

GOFORTH SUDGUADALUPE

41

49

56

64

73

81

L

GONZALES COUNTY WSC

GUADALUPE

58

70

83

95

91

102

L

IRRIGATION, CALDWELL

COLORADO

10

9

8

7

6

6

L

IRRIGATION, CALDWELLGUADALUPE

309

274

244

217

192

175

L

LIVESTOCK, CALDWELL

COLORADO

37

37

37

37

37

37

L

LIVESTOCK, CALDWELLGUADALUPE

483

483

483

483

483

483

L

LOCKHARTGUADALUPE

2,251

2,676

3,105

3,547

4,010

4,465

L

LULINGGUADALUPE

950

1,125

1,301

1,484

1,678

1,868

L

MANUFACTURING, CALDWELLGUADALUPE

4

5

5

6

6

7

L

MARTINDALE

GUADALUPE

187

221

256

292

330

367

L

MAXWELL WSC

GUADALUPE

414

487

561

638

720

802

L

MINING, CALDWELL

COLORADO

6

5

3

2

1

1

46

34

22

9

4

L

MINING, CALDWELLGUADALUPE

58

L

MUSTANG RIDGECOLORADO

69

82

95

108

122

136

L

MUSTANG RIDGEGUADALUPE

2

2

2

3

3

3

L

NIEDERWALDGUADALUPE

16

19

22

25

28

31

L

POLONIA WSC

COLORADO

282

333

386

440

498

554

L

POLONIA WSC

GUADALUPE

596

707

819

935

1,055

1,175

L

SAN MARCOSGUADALUPE

2

3

4

5

6

7

L

UHLANDGUADALUPE

79

94

110

126

142

158

6,738

7,772

8,825

9,920

11,054

12,203Sum of Projected Water Demands (acre-feet)

HAYS COUNTY

9.11% (multiplier)

All values are in acre-feet

RWPG

WUG

WUG Basin

2020

2030

2040

2050

2060

2070

K

AUSTINCOLORADO

13

127

249

631

1,519

2,749

Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

K

BUDA

COLORADO

1,769

2,508

3,420

4,564

5,860

7,338

K

CIMARRON PARK WATERCOMPANYCOLORADO

249

241

234

230

229

229

K

COUNTY-OTHER, HAYSCOLORADO

283

337

421

517

599

681

K

DRIPPING SPRINGSCOLORADO

479

537

610

704

813

938

K

DRIPPING SPRINGS WSC

COLORADO

533

680

861

1,091

1,353

1,652

K

GOFORTH SUD

COLORADO

85

130

185

255

334

425

K

IRRIGATION, HAYSCOLORADO

10

10

10

10

10

10

K

LIVESTOCK, HAYSCOLORADO

20

20

20

20

20

20

K

MANUFACTURING, HAYSCOLORADO

32

36

41

45

49

53

K

MINING, HAYSCOLORADO

77

98

124

132

151

172

K

MOUNTAIN CITY

COLORADO

57

56

54

54

54

54

K

PLUM CREEK WATER COMPANY COLORADO

163

264

283

300

312

322

K

WEST TRAVIS COUNTY PUBLIC COLORADOUTILITY AGENCY

4,093

5,758

7,795

10,343

13,226

16,508L

BUDA

GUADALUPE

299

388

499

639

798

979

L

COUNTY LINE WSC

GUADALUPE

181

231

298

383

478

587

L

COUNTY-OTHER, HAYSGUADALUPE

188

208

416

572

1,077

1,638

L

CREEDMOOR-MAHA WSC

GUADALUPE

10

12

15

19

23

28

L

CRYSTAL CLEAR WSC

GUADALUPE

632

717

827

973

1,143

1,338

L

GOFORTH SUDGUADALUPE

1,384

1,753

2,220

2,818

3,504

4,287

L

IRRIGATION, HAYSGUADALUPE

59

59

58

58

57

56

L

KYLE

GUADALUPE

5,156

7,680

9,133

9,119

9,108

9,104

37

37

37

37

37

L

LIVESTOCK, HAYSGUADALUPE

37

L

MANUFACTURING, HAYSGUADALUPE

10

11

13

14

15

16

L

MAXWELL WSC

GUADALUPE

117

122

131

144

160

179

L

MOUNTAIN CITYGUADALUPE

24

30

38

48

60

73

L

NIEDERWALDGUADALUPE

59

75

96

122

151

185

L

PLUM CREEK WATER COMPANY GUADALUPE

736

1,068

1,048

1,032

1,019

1,009

L

SAN MARCOSGUADALUPE

11,934

13,941

16,43019,48523,20527,655L

STEAM ELECTRIC POWER,HAYSGUADALUPE

67

88

181

247

336

458

L

UHLANDGUADALUPE

99

133

175

229

290

360

800

1,018

1,300

1,622

1,990

L

WIMBERLEYGUADALUPE

626

L

WIMBERLEY WSC

GUADALUPE

450

657

919

1,247

1,617

2,039

L

WOODCREEKGUADALUPE

282

311

349

399

458

525

30,21339,12348,20857,781

69,687

83,694

Sum of Projected Water Demands (acre-feet)

Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

Projected Water Supply Needs
TWDB 2017 State Water Plan Data
Negative values (in red) reflect a projected water supply need, positive values a surplus.

All values are in acre-feet

CALDWELL COUNTY
RWPG

WUG

WUG Basin

2020

2030

2040

2050

2060

2070

L

AQUA WSC

COLORADO

43

35

26

18

9

0

L

AQUA WSCGUADALUPE

242

195

148

99

49

0

L

COUNTY LINE WSC

GUADALUPE

56

19

-22

-64

-104

-141

L

COUNTY-OTHER, CALDWELL

COLORADO

182

173

163

154

143

133

L

COUNTY-OTHER, CALDWELLGUADALUPE

1,108

986

862

732

596

462

L

CREEDMOOR-MAHA WSC

COLORADO

0

0

0

0

0

0

L

CREEDMOOR-MAHA WSC

GUADALUPE

0

0

0

0

0

0

L

GOFORTH SUDGUADALUPE

0

0

0

0

0

0

L

GONZALES COUNTY WSC

GUADALUPE

14

11

4

-3

6

-3

L

IRRIGATION, CALDWELL

COLORADO

0

2

4

6

7

8

L

IRRIGATION, CALDWELLGUADALUPE

34

101

160

213

261

294

L

LIVESTOCK, CALDWELL

COLORADO

0

0

0

0

0

0

L

LIVESTOCK, CALDWELLGUADALUPE

0

0

0

0

0

0

L

LOCKHARTGUADALUPE

-188

-613

-1,042-1,484-1,947-2,402L

LULINGGUADALUPE

133

-41

-217

-400

-594

-784

L

MANUFACTURING, CALDWELLGUADALUPE

5

4

3

2

1

0

L

MARTINDALE

GUADALUPE

3

-31

-66

-102

-140

-177

L

MAXWELL WSC

GUADALUPE

624

578

519

448

368

286

L

MINING, CALDWELL

COLORADO

0

0

0

0

0

0

L

MINING, CALDWELLGUADALUPE

0

0

0

0

0

0

L

MUSTANG RIDGECOLORADO

0

0

0

0

0

0

L

MUSTANG RIDGEGUADALUPE

0

0

0

0

0

0

L

NIEDERWALDGUADALUPE

-13

-16

-20

-23

-26

-29

L

POLONIA WSC

COLORADO

118

65

11

-45

-104

-164

L

POLONIA WSC

GUADALUPE

262

146

26

-101

-237

-377

L

SAN MARCOSGUADALUPE

1

0

-1

-1

-2

-3

L

UHLANDGUADALUPE

0

0

0

0

0

0

-201

-701

-1,368-2,223-3,154-4,080Sum of Projected Water Supply Needs (acre-feet)

HAYS COUNTY

All values are in acre-feet

RWPG

WUG

WUG Basin

2020

2030

2040

2050

2060

2070

K

AUSTINCOLORADO

0

0

0

0

0

0

K

BUDA

COLORADO

161

-667

-1,690-2,974-4,429-6,088Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

K

CIMARRON PARK WATERCOMPANYCOLORADO

0

8

15

19

20

20

K

COUNTY-OTHER, HAYSCOLORADO

983

394

-530

-1,587-2,489-3,382K

DRIPPING SPRINGSCOLORADO

27

-31

-104

-198

-307

-432

K

DRIPPING SPRINGS WSC

COLORADO

0

0

0

0

0

-126

K

GOFORTH SUD

COLORADO

0

0

0

0

0

0

K

IRRIGATION, HAYSCOLORADO

333

333

333

333

333

333

K

LIVESTOCK, HAYSCOLORADO

2

2

2

2

2

2

K

MANUFACTURING, HAYSCOLORADO

236

185

134

88

46

0

K

MINING, HAYSCOLORADO

-531

-761

-1,047-1,131-1,340-1,579K

MOUNTAIN CITY

COLORADO

0

0

0

0

0

0

K

PLUM CREEK WATER COMPANY COLORADO

0

0

0

0

0

0

K

WEST TRAVIS COUNTY PUBLIC COLORADOUTILITY AGENCY

728

-937

-2,974-5,522-8,405-11,687L

BUDA

GUADALUPE

0

0

0

0

0

0

L

COUNTY LINE WSC

GUADALUPE

122

45

-56

-187

-336

-500

L

COUNTY-OTHER, HAYSGUADALUPE

3,101

2,881

601

-1,109-6,654-12,812L

CREEDMOOR-MAHA WSC

GUADALUPE

0

0

0

0

0

0

L

CRYSTAL CLEAR WSC

GUADALUPE

84

-13

-118

-243

-388

-551

L

GOFORTH SUDGUADALUPE

2,763

2,340

1,810

1,133

358

-525

L

IRRIGATION, HAYSGUADALUPE

88

94

100

106

112

118

L

KYLE

GUADALUPE

1,176-1,348-2,801-2,787-2,776-2,783

L

LIVESTOCK, HAYSGUADALUPE

0

0

0

0

0

0

L

MANUFACTURING, HAYSGUADALUPE

573

558

542

528

515

501

L

MAXWELL WSC

GUADALUPE

176

144

120

101

83

64

L

MOUNTAIN CITYGUADALUPE

4

-1

-7

-17

-29

-42

L

NIEDERWALDGUADALUPE

-49

-65

-85

-111

-140

-174

L

PLUM CREEK WATER COMPANY GUADALUPE

248

-185

-184

-185

-184

-184

L

SAN MARCOSGUADALUPE

1,867

-140

-2,629-5,685-9,405-13,855

L

STEAM ELECTRIC POWER,HAYSGUADALUPE

4,646

4,411

3,394

2,668

1,688

353

L

UHLANDGUADALUPE

0

0

0

0

0

0

L

WIMBERLEYGUADALUPE

218

44

-174

-456

-778

-1,146L

WIMBERLEY WSC

GUADALUPE

233

26

-236

-564

-934

-1,356L

WOODCREEKGUADALUPE

716

687

649

599

540

473

-580

-4,148-12,635-22,756-38,594-57,222

Sum of Projected Water Supply Needs (acre-feet)

Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

Projected Water Management Strategies
TWDB 2017 State Water Plan Data

CALDWELL COUNTYWUG, Basin (RWPG)
Water Management Strategy

All values are in acre-feet
Source Name [Origin]

2020

2030

2040

2050

2060

2070

COUNTY LINE WSC, GUADALUPE (L )BRACKISH WILCOX GROUNDWATERFOR CRWACARRIZO-WILCOXAQUIFER [WILSON]

0

0

0

64

105

141

CRWA SIESTA PROJECTDIRECT REUSE [BEXAR]

0

0

10

0

0

0

CRWA SIESTA PROJECTSAN ANTONIO RUN-OFRIVER [WILSON]

0

0

12

0

0

0

REUSE - KYLE/COUNTY LINE WSC

DIRECT REUSE [HAYS]

16

15

14

13

12

11

16

15

36

77

117

152

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

2

0

0

0

0

0

2

GBRA - MBWSP - SURFACE WATER W/ GUADALUPE RUN-OFASR (OPTION 3C)
RIVER [GONZALES]

0

0

0

0

0

0

MUNICIPAL WATER CONSERVATION(RURAL)

0

0

0

0

0

0

0

0

0

0

0

0

COUNTY-OTHER, CALDWELL, COLORADO (L )MUNICIPAL WATER CONSERVATION(RURAL)

DEMAND REDUCTION[CALDWELL]

COUNTY-OTHER, CALDWELL, GUADALUPE (L )MUNICIPAL WATER CONSERVATION(RURAL)

DEMAND REDUCTION[CALDWELL]

GOFORTH SUD, GUADALUPE (L )DEMAND REDUCTION[CALDWELL]GONZALES COUNTY WSC, GUADALUPE (L )LOCAL CARRIZO AQUIFER
DEVELOPMENTCARRIZO-WILCOXAQUIFER [GONZALES]

0

0

0

3

3

3

MUNICIPAL WATER CONSERVATION(RURAL)

DEMAND REDUCTION[CALDWELL]

8

12

20

29

32

42

8

12

20

32

35

45

DROUGHT MANAGEMENT - LOCKHART DEMAND REDUCTION[CALDWELL]

113

0

0

0

0

0

GBRA - MBWSP - SURFACE WATER W/ GUADALUPE RUN-OFASR (OPTION 3C)
RIVER [GONZALES]

1,120

1,120

1,120

1,484

1,947

2,402

0

0

0

0

0

72

1,233

1,120

1,120

1,484

1,947

2,474

1,673

1,674

1,674

1,673

1,678

1,868

LOCKHART, GUADALUPE (L )MUNICIPAL WATER CONSERVATION(SUBURBAN)

DEMAND REDUCTION[CALDWELL]

LULING, GUADALUPE (L )GBRA - MBWSP - SURFACE WATER W/ GUADALUPE RUN-OF-

Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

ASR (OPTION 3C)

RIVER [GONZALES]MUNICIPAL WATER CONSERVATION(RURAL)

DEMAND REDUCTION[CALDWELL]

0

0

0

0

0

3

1,673

1,674

1,674

1,673

1,678

1,871

MARTINDALE, GUADALUPE (L )DROUGHT MANAGEMENT MARTINDALE

DEMAND REDUCTION[CALDWELL]

9

0

0

0

0

0

HAYS/CALDWELL PUA PROJECTCARRIZO-WILCOXAQUIFER [CALDWELL]

0

31

66

102

140

177

MUNICIPAL WATER CONSERVATION(RURAL)

DEMAND REDUCTION[CALDWELL]

0

0

0

0

0

1

9

31

66

102

140

178

0

0

0

0

0

1

0

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

0

DEMAND REDUCTION[CALDWELL]

1

0

0

0

0

0

GBRA - MBWSP - SURFACE WATER W/ GUADALUPE RUN-OFRIVER [GONZALES]ASR (OPTION 3C)

13

16

20

23

26

29

14

16

20

23

26

29

0

0

0

45

104

164

0

0

0

45

104

164

0

0

0

101

237

377

0

0

0

101

237

377

GBRA - MBWSP - SURFACE WATER W/ GUADALUPE RUN-OFASR (OPTION 3C)
RIVER [GONZALES]

0

0

1

1

1

1

HAYS/CALDWELL PUA PROJECTCARRIZO-WILCOXAQUIFER [CALDWELL]

0

0

0

1

1

2

MUNICIPAL WATER CONSERVATION(SUBURBAN)

DEMAND REDUCTION[CALDWELL]

0

0

0

0

1

1

REUSE - SAN MARCOSDIRECT REUSE [HAYS]

0

1

1

1

2

2

0

1

2

3

5

6

0

0

0

0

2

6

0

0

0

0

2

6

2,953

2,869

2,938

3,540

4,291

5,305

MUSTANG RIDGE, COLORADO (L )MUNICIPAL WATER CONSERVATION(RURAL)

DEMAND REDUCTION[CALDWELL]MUSTANG RIDGE, GUADALUPE (L )MUNICIPAL WATER CONSERVATION(RURAL)

DEMAND REDUCTION[CALDWELL]

NIEDERWALD, GUADALUPE (L )DROUGHT MANAGEMENT NIEDERWALDPOLONIA WSC, COLORADO (L )LOCAL CARRIZO AQUIFER WITHCONVERSIONCARRIZO-WILCOXAQUIFER [CALDWELL]

POLONIA WSC, GUADALUPE (L )LOCAL CARRIZO AQUIFER WITHCONVERSIONCARRIZO-WILCOXAQUIFER [CALDWELL]

SAN MARCOS, GUADALUPE (L )UHLAND, GUADALUPE (L )MUNICIPAL WATER CONSERVATION(RURAL)

DEMAND REDUCTION[CALDWELL]

Sum of Projected Water Management Strategies (acre-feet)

Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

HAYS COUNTYWUG, Basin (RWPG)
Water Management Strategy

All values are in acre-feet
Source Name [Origin]

2020

2030

2040

2050

2060

2070

1

13

25

63

152

275

1

13

25

63

152

275

AUSTIN, COLORADO (K )DROUGHT MANAGEMENT

DEMAND REDUCTION[HAYS]

BUDA, COLORADO (K )DIRECT REUSE - BUDA

DIRECT REUSE [HAYS]

2,240

2,240

1,740

1,740

1,740

1,740

DROUGHT MANAGEMENT

DEMAND REDUCTION[HAYS]

177

251

342

456

586

734

EDWARDS / MIDDLE TRINITY ASR

TRINITY AQUIFER ASR[HAYS]

0

600

600

600

600

600

HCPUA PIPELINE - REGION K
RECOMMENDEDCARRIZO-WILCOXAQUIFER [GONZALES]

0

667

1,690

2,467

2,467

2,467

MUNICIPAL CONSERVATION - BUDA

DEMAND REDUCTION[HAYS]

88

206

434

552

709

888

SALINE EDWARDS ASREDWARDS AQUIFER ASR[TRAVIS]

0

100

100

100

100

100

SALINE EDWARDS ASR (SALINE)

EDWARDS-BFZ AQUIFER[TRAVIS]

0

400

400

400

400

400

2,505

4,464

5,306

6,315

6,602

6,929

COUNTY-OTHER, HAYS, COLORADO (K )BRUSH CONTROLCOLORADO RUN-OFRIVER [HAYS]

425

425

425

425

425

425

DROUGHT MANAGEMENT

DEMAND REDUCTION[HAYS]

466

554

693

852

987

1,121

EDWARDS / MIDDLE TRINITY ASR

TRINITY AQUIFER ASR[HAYS]

0

200

200

200

200

200

HAYS COUNTY PIPELINE - REGION K
RECOMMENDEDCARRIZO-WILCOXAQUIFER [GONZALES]

0

2,000

2,000

2,000

2,000

2,000

SALINE EDWARDS ASREDWARDS AQUIFER ASR[TRAVIS]

0

100

100

100

100

100

SALINE EDWARDS ASR (SALINE)

EDWARDS-BFZ AQUIFER[TRAVIS]

0

100

100

100

100

100

891

3,379

3,518

3,677

3,812

3,946

DRIPPING SPRINGS, COLORADO (K )DROUGHT MANAGEMENT

DEMAND REDUCTION[HAYS]

96

107

122

141

163

188

HAYS COUNTY PIPELINE - REGION K
RECOMMENDEDCARRIZO-WILCOXAQUIFER [GONZALES]

0

0

0

0

134

407

MUNICIPAL CONSERVATION DRIPPING SPRINGS

DEMAND REDUCTION[HAYS]

48

67

98

141

195

262

WATER PURCHASEHIGHLAND LAKES
LAKE/RESERVOIR SYSTEM[RESERVOIR]

0

31

104

198

173

0

144

205

324

480

665

857

107

136

172

218

271

330

DRIPPING SPRINGS WSC, COLORADO (K )DROUGHT MANAGEMENT

DEMAND REDUCTION

Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

[HAYS]HAYS COUNTY PIPELINE - REGION K
RECOMMENDEDCARRIZO-WILCOXAQUIFER [GONZALES]

0

1,000

1,000

1,000

866

593

MUNICIPAL CONSERVATION DRIPPING SPRINGS WSC

DEMAND REDUCTION[HAYS]

54

124

152

187

232

283

161

1,260

1,324

1,405

1,369

1,206

DEMAND REDUCTION[HAYS]

21

33

46

64

84

106

GBRA - MBWSP - SURFACE WATER W/ GUADALUPE RUN-OFASR (OPTION 3C)
RIVER [GONZALES]

0

0

0

0

0

0

MUNICIPAL WATER CONSERVATION(RURAL)

0

0

0

0

0

0

21

33

46

64

84

106

GOFORTH SUD, COLORADO (K )DROUGHT MANAGEMENT

DEMAND REDUCTION[HAYS]MINING, HAYS, COLORADO (K )DIRECT REUSE - BUDA

DIRECT REUSE [HAYS]

0

0

500

500

500

500

EDWARDS / MIDDLE TRINITY ASR

TRINITY AQUIFER ASR[HAYS]

0

100

100

100

100

100

EXPANSION OF CURRENTGROUNDWATER SUPPLIES - TRINITYAQUIFER

TRINITY AQUIFER [HAYS]

531

761

1,047

1,047

1,047

1,047

531

861

1,647

1,647

1,647

1,647

PLUM CREEK WATER COMPANY, COLORADO (K )DROUGHT MANAGEMENT

DEMAND REDUCTION[HAYS]

8

13

14

15

16

16

HAYS/CALDWELL PUA PROJECTCARRIZO-WILCOXAQUIFER [CALDWELL]

0

37

39

42

43

45

8

50

53

57

59

61

WEST TRAVIS COUNTY PUBLIC UTILITY AGENCY, COLORADO (K )DROUGHT MANAGEMENT

DEMAND REDUCTION[HAYS]

819

1,152

1,559

2,069

2,645

3,302

HAYS COUNTY PIPELINE - REGION K
RECOMMENDEDCARRIZO-WILCOXAQUIFER [GONZALES]

0

1,000

1,000

1,000

1,000

1,000

LCRA - LANE CITY RESERVOIRLCRA NEW OFF-CHANNELRESERVOIRS (2020
DECADE) [RESERVOIR]

0

500

2,700

3,000

5,800

5,800

MUNICIPAL CONSERVATION - WESTTRAVIS COUNTY PUA

DEMAND REDUCTION[HAYS]

405

1,070

2,064

3,501

5,348

7,674

1,224

3,722

7,323

9,570

14,793

17,776

COUNTY LINE WSC, GUADALUPE (L )BRACKISH WILCOX GROUNDWATERFOR CRWACARRIZO-WILCOXAQUIFER [WILSON]

0

0

0

187

335

500

CRWA SIESTA PROJECTDIRECT REUSE [BEXAR]

0

0

25

0

0

0

CRWA SIESTA PROJECTSAN ANTONIO RUN-OFRIVER [WILSON]

0

0

31

0

0

0

REUSE - KYLE/COUNTY LINE WSC

DIRECT REUSE [HAYS]

34

35

36

37

38

39

34

35

92

224

373

539

GBRA - MBWSP - SURFACE WATER W/ GUADALUPE RUN-OFASR (OPTION 3C)
RIVER [GONZALES]

0

0

0

0

2,029

7,220

TWA REGIONAL CARRIZO AQUIFER

0

0

0

1,169

4,685

4,388

COUNTY-OTHER, HAYS, GUADALUPE (L )CARRIZO-WILCOX

Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

DEVELOPMENTAQUIFER [GONZALES]TWA TRINITY AQUIFER
DEVELOPMENT

TRINITY AQUIFER[COMAL]VISTA RIDGE PROJECTCARRIZO-WILCOXAQUIFER [BURLESON]

0

0

0

0

0

1,263

3,781

5,000

5,000

5,000

5,000

5,000

3,781

5,000

5,000

6,169

11,714

17,871

CRWA WELLS RANCH PROJECT PHASE CARRIZO-WILCOXIIAQUIFER [GUADALUPE]

75

261

317

0

0

0

HAYS/CALDWELL PUA PROJECTCARRIZO-WILCOXAQUIFER [CALDWELL]

124

296

243

577

597

621

MUNICIPAL WATER CONSERVATION(RURAL)

DEMAND REDUCTION[HAYS]

0

0

0

0

0

22

199

557

560

577

597

643

GBRA - MBWSP - SURFACE WATER W/ GUADALUPE RUN-OFASR (OPTION 3C)
RIVER [GONZALES]

0

0

0

0

0

525

MUNICIPAL WATER CONSERVATION(RURAL)

0

0

0

0

0

2

0

0

0

0

0

527

CRYSTAL CLEAR WSC, GUADALUPE (L )GOFORTH SUD, GUADALUPE (L )DEMAND REDUCTION[HAYS]

KYLE, GUADALUPE (L )HAYS/CALDWELL PUA PROJECTCARRIZO-WILCOXAQUIFER [CALDWELL]

0

1,163

2,616

2,602

2,591

2,598

MUNICIPAL WATER CONSERVATION(SUBURBAN)

DEMAND REDUCTION[HAYS]

0

0

0

53

266

480

REUSE - KYLE/COUNTY LINE WSC

DIRECT REUSE [HAYS]

2,329

3,591

4,318

4,284

4,172

4,063

2,329

4,754

6,934

6,939

7,029

7,141

DROUGHT MANAGEMENT - MOUNTAIN DEMAND REDUCTIONCITY[HAYS]

1

0

0

0

0

0

EDWARDS / MIDDLE TRINITY ASR

TRINITY AQUIFER ASR[HAYS]

0

44

44

44

44

44

LOCAL TRINITY AQUIFER
DEVELOPMENT

TRINITY AQUIFER [HAYS]

60

60

60

60

60

60

MUNICIPAL WATER CONSERVATION(RURAL)

DEMAND REDUCTION[HAYS]

0

0

0

0

0

1

61

104

104

104

104

105

DEMAND REDUCTION[HAYS]

3

0

0

0

0

0

GBRA - MBWSP - SURFACE WATER W/ GUADALUPE RUN-OFASR (OPTION 3C)
RIVER [GONZALES]

49

65

85

111

140

174

52

65

85

111

140

174

MOUNTAIN CITY, GUADALUPE (L )NIEDERWALD, GUADALUPE (L )DROUGHT MANAGEMENT NIEDERWALD

PLUM CREEK WATER COMPANY, GUADALUPE (L )HAYS/CALDWELL PUA PROJECTCARRIZO-WILCOXAQUIFER [CALDWELL]

0

148

146

143

142

140

LOCAL TRINITY AQUIFER
DEVELOPMENT

TRINITY AQUIFER [HAYS]

0

185

185

185

185

185

0

333

331

328

327

325

SAN MARCOS, GUADALUPE (L )Estimated Historical Water Use and 2017 State Water
Plan Dataset:
Plum Creek Conservation District
September 20, 2017

GBRA - MBWSP - SURFACE WATER W/ GUADALUPE RUN-OFASR (OPTION 3C)
RIVER [GONZALES]

0

0

2,379

3,470

4,580

5,716

HAYS/CALDWELL PUA PROJECTCARRIZO-WILCOXAQUIFER [CALDWELL]

0

0

0

1,964

4,575

7,889

MUNICIPAL WATER CONSERVATION(SUBURBAN)

DEMAND REDUCTION[HAYS]

179

778

1,122

1,684

2,506

3,587

REUSE - SAN MARCOSDIRECT REUSE [HAYS]

1,932

2,886

3,959

5,206

6,654

8,339

2,111

3,664

7,460

12,324

18,31525,531

0

0

0

0

3

13

0

0

0

0

3

13

GBRA - MBWSP - SURFACE WATER W/ GUADALUPE RUN-OFASR (OPTION 3C)
RIVER [GONZALES]

0

0

74

356

678

933

MUNICIPAL WATER CONSERVATION(RURAL)

DEMAND REDUCTION[HAYS]

10

55

78

123

187

272

TWA REGIONAL CARRIZO AQUIFER
DEVELOPMENTCARRIZO-WILCOXAQUIFER [GONZALES]

0

0

100

100

100

100

TWA TRINITY AQUIFER
DEVELOPMENT

TRINITY AQUIFER[COMAL]

0

0

0

0

0

113

10

55

252

579

965

1,418

GBRA - MBWSP - SURFACE WATER W/ GUADALUPE RUN-OFASR (OPTION 3C)
RIVER [GONZALES]

0

0

136

464

834

1,123

TWA REGIONAL CARRIZO AQUIFER
DEVELOPMENTCARRIZO-WILCOXAQUIFER [GONZALES]

0

0

100

100

100

100

TWA TRINITY AQUIFER
DEVELOPMENT

TRINITY AQUIFER[COMAL]

0

0

0

0

0

133

0

0

236

564

934

1,356

10

25

31

41

57

76
76

UHLAND, GUADALUPE (L )MUNICIPAL WATER CONSERVATION(RURAL)

DEMAND REDUCTION[HAYS]WIMBERLEY, GUADALUPE (L )WIMBERLEY WSC, GUADALUPE (L )WOODCREEK, GUADALUPE (L )MUNICIPAL WATER CONSERVATION(SUBURBAN)

DEMAND REDUCTION[HAYS]

Sum of Projected Water Management Strategies (acre-feet)
88,522

10

25

31

41

57

14,07328,57940,651

51,23869,741GAM RuN 16-033 MAG: MODELED
AVAILABLE GROUNDWATER FOR THE
AQUIFERS IN GROUNDWATER MANAGEMENTAREA1O
Robert G. Bradley, P.G. and Radu Boghici, P.G.
Texas Water Development Board
Groundwater Division(512] 463-5808
July 20, 2018

This page is intentionally left blank.

GAM RUN 16-033 MAG:
MODELED AVAILABLE GROUNDWATER
AQUIFERS IN GROUNDWATER MANAGEMENT AREA
10EXECUTIVE SUMMARY:

Robert G. Bradley, P.G. and Radu Boghici, P.G.
Texas Water Development Board
Groundwater Division(512) 463-5808
July 20, 2018

The modeled available groundwater for the relevant aquifers of Groundwater Management
Area 10—the Austin Chalk-Buda Limestone (relevant in Uvalde County), Barton Springs
segment of the Edwards (Balcones Fault Zone), saline portion of the Barton Springs
segment of the Edwards (Balcones Fault Zone), western portion of the San Antonio
segment of the Edwards (Balcones Fault Zone) in Kinney County, Leona Gravel (relevant in
Uvalde County), and Trinity—are summarized for the groundwater conservation districts(Tables 1, 3, 5, and 8) and by decade for use in the regional water planning process (Tables
2, 4, 6, and 9) . The modeled available groundwater estimates are 2,935 acre-feet per year
in the Austin Chalk Aquifer (Uvalde County); 758 acre-feet per year in the Buda Limestone
Aquifer (Uvalde County); 11,557 acre-feet per year in the Barton Springs segment of the
Edwards (Balcones Fault Zone) Aquifer during average recharge conditions (3,765 acrefeet per year during drought conditions); 8,564 acre-feet per year in the saline portion of
the Barton Springs segment of the Edwards (Balcones Fault Zone) Aquifer; 6,321 acre-feetper year in the freshwater portion of the western part of the San Antonio segment of the
Edwards (Balcones Fault Zone) Aquifer; 9,385 acre-feet per year in the Leona Gravel
Aquifer (Uvalde County); and 46,481 acre-feet per year in the Trinity Aquifer. Appropriate
groundwater availability models were used to determine the modeled available
groundwater for the Kinney County area of the Edwards (Balcones Fault Zone) Aquifer andto determine average recharge conditions for the Barton Springs segment of the Edwards(Balcones Fault Zone) Aquifer. Water budget methods were used to calculate the modeled
available groundwater for the rest of the relevant aquifers in Groundwater Management
Area 10. The Texas Water Development Board (TWDB) determined that the explanatory
report and other materials were administratively complete on February 12, 2018.

REQUESTOR:

Mr. John Dupnik, Chair of Groundwater Management Area 10.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 4 of 32

DESCRIPTION OF REQUEST:In a letter dated November 3, 2017, Mr. John Dupnik provided the TWDB with the desired
future conditions of the relevant aquifers in Groundwater Management Area 10. The
desired future conditions, adopted June 26, 2017, by the groundwater conservation
districts within Groundwater Management Area 10, are reproduced below:
Austin [Chalk-]Buda Limestone Aquifer(s), relevant in Uvalde County only:••

Buda Limestone: no drawdown (including exempt and non-exempt use); andAustin Chalk: no drawdown (including exempt and non-exempt use).

Freshwater Edwards Aquifer in the Northern [Groundwater Management Area 10]
Subdivision••

Springflow at Barton Springs during average recharge conditions shall be no lessthan 49.7 [cubic feet per second] averaged over an 84-month (7-year) period;and,Springflow of Barton Springs during extreme drought conditions, including thoseas severe as a recurrence of the 1950s drought of record, shall be no less than
6.5 [cubic feet per second] average on a monthly basis.

Saline Edwards Aquifer in the Northern [Groundwater Management Area 10]
Subdivision•

No more than 75 feet of regional average potentiometric surface drawdown due
to pumping when compared to pre-development.

Freshwater Edwards Aquifer in the Western [Groundwater Management Area 10]
Subdivision•

The water level in well 70-38-902 shall not fall below 1,184 [feet above] meansea level.

Leona Gravel Aquifer, relevant in Uvalde County only:•

No drawdown (including exempt and non-exempt use).

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 5 of 32

Trinity Aquifer, in hydrologically confined zone downdip of the Trinity outcrop:•••

Outside of Uvalde and Bexar counties: average regional well drawdown notexceeding 25 feet during average recharge conditions (including exempt andnon-exempt use);

In Uvalde County: no (zero) regional well drawdown (including exempt and nonexempt use); [and]In Bexar County: non-relevant for joint planning purpose.

In response to a request for clarifications from the TWDB on December 14, 2017, andJanuary 29, 2018 Mr. John Dupnik indicated the following preferences for calculating
modeled available groundwater volumes in Groundwater Management Area 10:
Austin Chalk-Buda Limestone aquifers (only in Uvalde County)

The TWDB will use the methods and assumptions from AA 10-26 MAG and AA 1027 MAG, with a planning period from 2010 to 2060.

Freshwater Edwards, Northern Subdivision

The TWDB will use the methods and assumptions from GAM Run 10-059 MAG
Version 2, with a planning period from 2010 to 2060. Groundwater Management
Area 10 specified two desired future conditions for this aquifer. We will provide
only the drought conditions modeled available groundwater for regional waterplanning purposes because this corresponds to the methods used in regional waterplanning (planning for water in times of drought). We will provide both the average
recharge conditions and the drought conditions modeled available groundwater inthe final report. The modeled available groundwater values will be unchanged fromthe previous planning cycle.

Saline Edwards, Northern Subdivision

The TWDB will use aquifer parameters from AA 10-35 MAG, with a planning period
from 2010 to 2060, but we will recalculate with a simple water budget as outlined inTable 1 of the Saline Edwards explanatory report, instead of the method used in AA
10-35 MAG. On January 29, 2018, we received Technical Memo 2017-1221 from theBarton Springs/ Edwards Aquifer Conservation District, which outlines the technicalclarification on the method to use for this aquifer.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 6 of 32

Freshwater Edwards, Western Subdivision (only in Kinney County)

The TWDB will use the methods and assumptions from GAM Run 12-002 MAG, witha planning period from 2010 to 2060. The modeled available groundwater values
will be unchanged from the previous planning cycle.

Leona Gravel (only in Uvalde County)

The TWDB will use the methods and assumptions from AA 10-28 MAG, with aplanning period from 2010 to 2060.

Trinity (downdip of recharge zone)

The TWDB will use the methods and assumptions from AA 10-06 with a planning
period from 2010 to 2060. The changes in groundwater district boundaries since AA
10-06 will require reapportionment of the modeled available groundwater.

METHODS:The desired future conditions for the Austin Chalk-Buda Limestone aquifers (relevant in
Uvalde County), Leona Gravel Aquifer (relevant in Uvalde County), Barton Springs segmentof the Edwards (Balcones Fault Zone) Aquifer, saline portion of the Barton Springs segmentof the Edwards (Balcones Fault Zone) Aquifer, Trinity Aquifer, and western portion of the
San Antonio segment of the Edwards (Balcones Fault Zone) Aquifer in Kinney County are
identical to the ones adopted in 2010. The applicable water budget methodologies tocalculate modeled available groundwater are unchanged except for the saline Edwards(Balcones Fault Zone) and Trinity aquifers.

Therefore, the modeled available groundwater volumes presented for most of the aquifers
are the same as those shown in the previous water budget assessments and model runs.
These reports are AA 10-26 MAG (Thorkildsen and Backhouse, 2011a), AA 10-27 MAG(Thorkildsen and Backhouse, 2011b), GAM Run 10-059 MAG Version 2 (Hutchison andOliver, 2011), GAM Run 12-002 MAG (Shi, 2012), and AA 10-28 MAG (Bradley, 2013).
The modeled available groundwater numbers were recalculated for the Trinity Aquifer toincorporate changes in the Groundwater Management Area 10 and groundwater
conservation district boundaries. Additionally, a change in methodology required therecalculation of the Saline Edwards (Balcones Fault Zone) Aquifer modeled available
groundwater, however, aquifer parameters from AA 10-35 MAG (Bradley, 2011) wereincorporated into this assessment.

For the water budget approaches, modeled available groundwater volumes were
determined by summing estimates of effective recharge and the change in aquifer storage.
The water budget for these analyses were a simplified version of one found in Freeze andCherry (1979, p.365).

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 7 of 32

This was the best method to calculate a modeled available groundwater estimate at thistime; however, this method has limitations and should be replaced with better tools,
including groundwater models and additional data as they become available. These
analyses assume homogeneous and isotropic aquifers; however, real aquifer conditions do
not satisfy these assumptions. These analyses further assume that precipitation is the only
source of aquifer recharge, that lateral inflow to the aquifer is equal to lateral outflow fromthe aquifer, and that future pumping will not alter this balance. In addition, certain
assumptions have been made regarding future precipitation, recharge, and streamflow indeveloping these estimates. Those assumptions also need to be considered and comparedto actual future data when evaluating achievement of the desired future condition.
Estimates of modeled available groundwater volumes from the numerical flow models
were determined by extracting pumping rates by decade from the model results using
ZONEBUDGET Version 3.01 (Harbaugh, 2009). Annual pumping rates were divided bycounty, river basin, regional water planning area, and groundwater conservation district
within Groundwater Management Area 10 (Figures 1 through 7 and Tables 1 through 9).

Modeled Available Groundwater and Permitting

Chapter 36 of the Texas Water Code defines “modeled available groundwater” to be theestimated average amount of water that may be produced annually to achieve a desired
future condition. Groundwater conservation districts are required to consider modeled
available groundwater, along with several other factors, when issuing permits to manage
groundwater production to achieve the desired future condition(s). Districts must also
consider include annual precipitation and production patterns, the estimated amount ofpumping exempt from permitting, existing permits, and a reasonable estimate of actual
groundwater production under existing permits.

PARAMETERS AND ASSUMPTIONS:
Austin Chalk-Buda Limestone Aquifers••

All parameters and assumptions for the Austin Chalk Aquifer are described in AA
10-26 MAG (Thorkildsen and Backhouse, 2011a) and for the Buda Limestone in
AA 10-27 MAG (Thorkildsen and Backhouse, 2011b). Both reports assumed aplanning period from 2010 to 2060.
The Austin Chalk Aquifer in Uvalde County is in a state of dynamic equilibrium
and the 2008 estimated pumpage of 2,935 acre-feet (Green and others, 2009)
achieves the adopted desired future condition.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 8 of 32••

The Buda Limestone Aquifer in Uvalde County is in a state of dynamic
equilibrium and the 2008 estimated pumpage of 758 acre-feet (Green andothers, 2009) achieves the adopted desired future condition.

Conditions are physically possible across the management area and a waterlevel decline of 0 feet is uniform across the aquifer(s).

Freshwater Edwards (Balcones Fault Zone) Aquifer

NORTHERN SUBDIVISION OF GROUNDWATER M ANAGEMENT AREA 10
•

•

•

•

•

All parameters and assumptions for the freshwater portion of the Edwards(Balcones Fault Zone) Aquifer in the northern subdivision of Groundwater
Management Area 10 are described in GAM Run 10-059 MAG Version 2(Hutchison and Oliver, 2011). Both approaches discussed below assumed a 50year planning period. From clarifications we received from Mr. John Dupnik, we
assume a 50-year planning period from 2010 to 2060.

A water balance approach was used to estimate modeled available groundwater
during extreme drought conditions 1 based on information provided by Barton
Springs/Edwards Aquifer Conservation District. See Hunt and others (2011) for
additional details on the methods and assumptions for this approach.

The total amount of water available for discharge by both springs and pumping
during extreme drought conditions (11.7 cubic feet per second or 8,470 acre-feetper year) was estimated using information from the 1950’s drought of record as
described in Hunt and (2011).

The water balance approach does not contain information about the spatial
distribution of pumping. For the purposes of regional water planning, theestimated total pumping available during extreme drought conditions was
divided by county, regional water planning area, river basin, and groundwater
conservation district based on the distribution of pumping in the modeled
approach under average recharge conditions (Hutchison and Oliver, 2011).

For average recharge conditions, we used the numerical groundwater flow
model that was recalibrated to include the 1950s drought for the Barton Springs
segment of the Edwards (Balcones Fault Zone) Aquifer. See Hutchison and Hill
(2011a) for assumptions and limitations of the numerical flow model.

1 The desired future conditions statement adopted by the district representatives in GMA 10 uses the term

“extreme drought conditions” to include the drought of record.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 9 of 32

•

•

•

The model does not cover the Edwards Aquifer (Balcones Fault Zone) in thesouthernmost Barton Springs/Edwards Aquifer Conservation Districtjurisdiction (see Figure 4). However, given that, during average recharge
conditions, the contributing zone for the flow at Barton Springs does not extend
this far south, we deemed the use of the model appropriate for this purpose.

Similar to GAM Run 09-019 (Hutchison and Hill, 2011b), the simulations
consisted of 342 7-year simulations extending from 1648 through 1995 basedon a tree-ring dataset from Cleaveland (2006). Each 7-year simulation consistedof 84 monthly stress periods.
Model simulations indicated that, during average recharge conditions, anaverage springflow of 49.7 cubic feet per second could be maintained byallowing 11,557 acre-feet per year pumping.

KINNEY COUNTY•••

All parameters and assumptions for the freshwater portion of the Edwards(Balcones Fault Zone) Aquifer in the western subdivision of Groundwater
Management Area 10 (Kinney County) are described in GAM Run 12-002 MAG(Shi, 2012). We used a 50-year planning period from 2010 to 2060.

We used version 1.01 of the numerical groundwater flow model of the Kinney
County Area. See Hutchison and others (2011) for assumptions and limitationsof the numerical groundwater flow model. The model was run with MODFLOW2000 (Harbaugh and others, 2000).

The model has four layers: layer 1 represents the Carrizo-Wilcox and associatedaquifers, layer 2 represents the upper Cretaceous formations that yield
groundwater, layer 3 represents the Edwards (Balcones Fault Zone) Aquifer andthe Edwards Group of the Edward-Trinity (Plateau) Aquifer, and layer 4
represents the Trinity Aquifer.

Saline Edwards (Balcones Fault Zone) Aquifer•

A detailed description of all parameters is available for the saline portion of the
Edwards (Balcones Fault Zone) Aquifer in the northern subdivision of
Groundwater Management Area 10 in AA 10-35 MAG (Bradley, 2011). Table 1
from Barton Springs/Edwards Aquifer Conservation District Technical Memo2017-1221 (Hunt, 2017) outlines the approach used to estimate modeled
available groundwater. We used a 50-year planning period from 2010 to 2060.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 10 of 32•••

Map areas (Figure 5) from AA 10-35 MAG (Bradley, 2011) were used to calculate
volumes based on a storage coefficient of 7.0 X 10-4 (Hunt and others, 2010) anda desired future condition of 75 feet of drawdown. Map areas are designated asPlum Creek Conservation District only where their jurisdiction does not overlap
with the Barton Springs/Edwards Aquifer Conservation District.
A water-level decline of 75 feet is uniform across the aquifer for the 50-yearplanning period.

The aquifer is homogeneous and isotropic, lateral inflow to the aquifer is equal
to lateral outflow from the aquifer, and future pumping will not alter thisbalance.

Leona Gravel Aquifer••

A detailed description of all parameters and assumptions is available for the
Leona Gravel Aquifer in Uvalde County in AA 10-28 MAG (Bradley, 2013). We
used a 50-year planning period from 2010 to 2060.

See George (2010) for assumptions and parameters used to estimate effective
recharge. Recharge is received mainly from inflow from the Edwards Aquifer(Green and others, 2008) with additional recharge from direct precipitation. The
period 1996 to 2011 was selected for analysis of J-27 water levels due to thestart of mandated management of the Edwards Aquifer in 1996.

Trinity Aquifer••

A detailed description of all parameters and assumptions is available in AA 1006 (Thorkildsen and Backhouse, 2010b). We used a 50-year planning period
from 2010 to 2060.

The methods and assumptions used to estimate modeled available groundwater
for the Trinity Aquifer remain unchanged from AA 10-06 (Thorkildsen andBackhouse, 2010b). Because the Groundwater Management Area 10 boundary
was adjusted since the last round of joint planning, this required areapportionment of the modeled available groundwater as estimated in theoriginal aquifer assessment. First, changes were made to the Groundwater
Management Area 10 boundary to exclude the Guadalupe County, Hays Trinity,and Trinity Glen Rose groundwater conservation districts. There were alsochanges in to the Barton Springs/Edwards Aquifer Conservation District
boundary to include a portion of the Trinity Aquifer in Hays County.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 11 of 32

•

•

•

•

•

•
•

Bexar County is excluded from the modeled available groundwater calculations
because the groundwater management area designated the Trinity Aquifer in
Bexar County not relevant for joint planning.
Outcrop areas are calculated as unconfined areas of the aquifer and subcrop
areas are calculated as confined areas of the aquifer. Map areas 1-10 represent
outcrop areas, and map areas 11-31 are subcrop areas (see Figure 8 and Table
7).

Recharge is assigned only to the outcrop areas. The average annual precipitationfor outcrop map areas was determined from the Texas Climatic Atlas(Narasimhan and others, 2008), which is the average for years 1971 to 2000; thevalues range from 29 to 36 inches per year. The effective recharge rate isestimated to be 4 percent. The effective recharge calculation is the map area, inacres, multiplied by the estimated average annual precipitation, in feet, and theeffective recharge rate, in percent.
Lateral inflow to the Trinity Aquifer in Groundwater Management Area 10 isestimated to be 46,018 acre-feet per year based on the average outflow acrossthe Balcones Fault Zone results (Scenario 6) from GAM Task 10-005 (Hutchison,2010). This volume was apportioned across each county by aquifer map areas.
GAM Task 10-005 does not include inflows to Uvalde County, so a proportionalamount based on inflow to Medina County was used to estimate the inflow to
Uvalde County.

The storage coefficient for the Trinity Aquifer subcrop is assumed to be 1 X 10-5
derived from aquifer tests of the Trinity Aquifer subcrop in Travis and Hays
counties (Hunt and others, 2010). The storage coefficient for the Trinity Aquifer
subcrop in the remaining counties is assumed to be 5 X 10-5 as derived from thecalibrated groundwater availability model for the Hill Country portion of the
Trinity Aquifer system in Texas (Jones and others, 2009). The average specificyield of the Trinity Aquifer outcrop is estimated to be 5 X 10-2 (Ashworth, 1983).
Water-level drawdowns are uniform across the aquifer. Annual volumes fromdrawdowns are calculated by dividing the total volume by 50 years.

Modeled available groundwater estimates are the sum of the effective recharge,
lateral inflow, and volume from water-level decline.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 12 of 32

RESULTS:

Tables 1 through 6 and 8 through 9 show the combination of modeled available
groundwater summarized (1) by groundwater conservation district and county; and (2) bycounty, river basin, and regional water planning area for use in the regional water planning
process. The modeled available groundwater results for the groundwater conservation
districts (Tables 1, 3, 5, and 8), reflect the ending year discussed in the Parameters andAssumption Section of this report. For purposes of planning (Tables 2, 4, 6, and 9), thevalues may have been populated past the dates noted in Parameters and Assumption
Section using the trend of results.

The modeled available groundwater estimates are 2,935 acre-feet per year in the Austin
Chalk Aquifer (Uvalde County); 758 acre-feet per year in the Buda Limestone Aquifer(Uvalde County); 11,557 acre-feet per year in the Barton Springs segment of the Edwards(Balcones Fault Zone) Aquifer during average recharge conditions (3,765 acre-feet per year
during drought conditions); 8,564 acre-feet per year in the saline portion of the Barton
Springs segment of the Edwards (Balcones Fault Zone) Aquifer; 6,321 acre-feet per year in
the freshwater portion of the western part of the San Antonio segment of the Edwards(Balcones Fault Zone) Aquifer; 9,385 acre-feet per year in the Leona Gravel Aquifer (Uvalde
County); and 46,481 acre-feet per year in the Trinity Aquifer.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 13 of 32

FIGURE 1.

MAP SHOWING REGIONAL WATER PLANNING AREAS (RWPAS), GROUNDWATERCONSERVATION DISTRICTS (GCDS), AND COUNTIES IN THE VICINITY OF THE AUSTINCHALK AQUIFER IN UVALDE COUNTY.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 14 of 32

FIGURE 2.

MAP SHOWING REGIONAL WATER PLANNING AREAS (RWPAS), GROUNDWATERCONSERVATION DISTRICTS (GCDS), AND COUNTIES IN THE VICINITY OF THE BUDA
LIMESTONE AQUIFER IN UVALDE COUNTY.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 15 of 32

FIGURE 3.

MAP SHOWING REGIONAL WATER PLANNING AREAS (RWPAS), GROUNDWATERCONSERVATION DISTRICTS (GCDS), AND COUNTIES IN THE VICINITY OF THE
FRESHWATER AND SALINE EDWARDS (BALCONES FAULT ZONE) AQUIFER IN THE
NORTHERN SUBDIVISION OF GROUNDWATER MANAGEMENT AREA 10.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 16 of 32/

FIGURE 4.

MAP SHOWING GROUNDWATER AVAILABILITY MODEL EXTENT, EDWARDS(BALCONES FAULT ZONE) AQUIFER, AND ADMINISTRATIVE BOUNDARIES IN THE
NORTHERN PART OF THE BARTON SPRINGS/EDWARDS AQUIFER CONSERVATION
DISTRICT IN THE NORTHERN SUBDIVISION OF GROUNDWATER MANAGEMENT AREA
10.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 17 of 32

FIGURE 5.

MAP SHOWING AREAS USED FOR ESTIMATING THE SALINE, EDWARDS (BALCONESFAULT ZONE) AQUIFER, MODELED AVAILABLE GROUNDWATER IN THE NORTHERNSUBDIVISION OF GROUNDWATER MANAGEMENT AREA 10, (MODIFIED FROMBRADLEY,2011) .

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 18 of 32

FIGURE 6.

MAP SHOWING REGIONAL WATER PLANNING AREAS (RWPAS), GROUNDWATERCONSERVATION DISTRICTS (GCDS), AND COUNTIES IN THE VICINITY OF THE
FRESHWATER EDWARDS (BALCONES FAULT ZONE) AQUIFER IN THE WESTERNSUBDIVISION OF GROUNDWATER MANAGEMENT AREA 10 (KINNEY COUNTY).

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 19 of 32

FIGURE 7.

MAP SHOWING REGIONAL WATER PLANNING AREAS (RWPAS), GROUNDWATERCONSERVATION DISTRICTS (GCDS, UWCDS), AND COUNTIES IN THE VICINITY OF THE
LEONA GRAVEL AQUIFER IN GROUNDWATER MANAGEMENT AREA 10 (UVALDECOUNTY).

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 20 of 32

FIGURE 8

MAP SHOWING REGIONAL WATER PLANNING AREAS (RWPAS), GROUNDWATER CONSERVATION DISTRICTS (GCDS), AND
COUNTIES IN THE VICINITY OF THE TRINITY AQUIFER IN GROUNDWATER MANAGEMENT AREA 10.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 21 of 32

TABLE 1.

MODELED AVAILABLE GROUNDWATER FOR THE AUSTIN CHALK, BUDA LIMESTONE, AND LEONA GRAVEL AQUIFERS INUVALDE COUNTY IN GROUNDWATER MANAGEMENT AREA 10 FOR EACH DECADE BETWEEN 2010 AND 2060. VALUES ARE IN
ACRE-FEET PER YEAR.

Groundwater Conservation District

Uvalde County Underground Water Conservation District

CountyUvaldeTotal

TABLE 2.

CountyUvaldeAquifer

2010

2020

2030

2040

2050

2060

Austin Chalk

2,935

2,935

2,935

2,935

2,935

2,935

Leona Gravel

9,385

9,385

9,385

9,385

9,385

9,385

Buda Limestone758

16,013758

16,013758

16,013758

16,013758

758

16,01316,013

MODELED AVAILABLE GROUNDWATER FOR THE AUSTIN CHALK, BUDA LIMESTONE, AND LEONA GRAVEL AQUIFERS INUVALDE COUNTY IN GROUNDWATER MANAGEMENT AREA 10 SUMMARIZED BY COUNTY, REGIONAL WATER PLANNING AREA
(RWPA), AND RIVER BASIN FOR EACH DECADE BETWEEN 2020 AND 2070. VALUES ARE IN ACRE-FEET PER YEAR.
RWPA
L
Total

River Basin
NuecesAquifer

2020

2030

2040

2050

2060

2070

Austin Chalk

2,935

2,935

2,935

2,935

2,935

2,935

Leona Gravel

9,385

9,385

9,385

9,385

9,385

9,385

Buda Limestone758

16,013758

16,013758

16,013758

16,013758

16,013758

16,013

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 22 of 32

TABLE 3.

MODELED AVAILABLE GROUNDWATER FOR THE FRESHWATER PORTION OF THE EDWARDS (BALCONES FAULT ZONE)AQUIFER IN GROUNDWATER MANAGEMENT AREA 10 SUMMARIZED BY GROUNDWATER CONSERVATION DISTRICT (GCD)
AND COUNTY FOR EACH DECADE BETWEEN 2010 AND 2060. VALUES ARE IN ACRE-FEET PER YEAR.

Recharge
Condition

AverageGroundwater
Conservation District
Barton Springs/Edwards
Aquifer Conservation
District

CountyNon-District Areas

2040

2050

2060

7,950

7,950

7,950

7,950

7,950

Travis

3,578

3,578

3,578

3,578

3,578

3,578

Hays

29

29

29

29

29

29

11,557

11,557

11,557

11,557

11,557

11,557

Hays

2,590

2,590

2,590

2,590

2,590

2,590

Travis

1,166

1,166

1,166

1,166

1,166

1,166

Hays

9

9

9

9

9

9

3,765

3,765

3,765

3,765

3,765

3,765

6,321

6,321

6,321

6,321

6,321

6,321

Total for drought recharge conditions
Kinney County Groundwater Conservation
District

2030

7,950

Total for average recharge conditions

Drought

2020

Hays

Non-District Areas

Barton Springs/Edwards
Aquifer Conservation
District2010

KinneyGAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 23 of 32

TABLE 4.

Recharge Condition

Average

MODELED AVAILABLE GROUNDWATER FOR THE FRESHWATER PORTION OF THE EDWARDS (BALCONES FAULT ZONE)AQUIFER IN GROUNDWATER MANAGEMENT AREA 10 SUMMARIZED BY COUNTY, REGIONAL WATER PLANNING AREA (RWPA),
AND RIVER BASIN FOR EACH DECADE BETWEEN 2020 AND 2070. VALUES ARE IN ACRE-FEET PER YEAR.
CountyRWPA

River Basin

Hays

K

Colorado

7,037

7,037

7,037

7,037

7,037

7,037

TravisK

Colorado

3,578

11,557

3,578

11,557

3,578

11,557

3,578

11,557

3,578

11,557

3,578

11,557

Hays

K

Colorado

2,292

2,292

2,292

2,292

2,292

2,292

TravisK

Colorado

Total for drought recharge conditions

1,166

3,765

1,166

3,765

1,166

3,765

1,166

3,765

1,166

3,765

1,166

3,765

KinneyJ

Nueces

6,319

6,319

6,319

6,319

6,319

6,319

Hays

L

Guadalupe

Total for average recharge conditions

Drought

Not applicable

Hays

L

Guadalupe

Rio Grande

2020

2030

942

307

2

2040

942

307

2

2050

942

307

2

2060

942

307

2

2070

942

307

2

942

307

2

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 24 of 32

TABLE 5.

MODELED AVAILABLE GROUNDWATER FOR THE SALINE PORTION OF THE EDWARDS (BALCONES FAULT ZONE) AQUIFER INGROUNDWATER MANAGEMENT AREA 10 SUMMARIZED BY GROUNDWATER CONSERVATION DISTRICT (GCD) AND COUNTYFOR EACH DECADE BETWEEN 2010 AND 2060. VALUES ARE IN ACRE-FEET PER YEAR.
Groundwater
Conservation District
BartonSprings/Edwards
Aquifer Conservation
Non-District Areas
Plum Creek
Conservation District

TABLE 6.

Total

County

2010

2020

2030

2040

2050

2060

Caldwell
Hays
TravisCaldwellTravisCaldwell

858
1,171
1,770
369
3,583
210

858
1,171
1,770
369
3,583
210

858
1,171
1,770
369
3,583
210

858
1,171
1,770
369
3,583
210

858
1,171
1,770
369
3,583
210

858
1,171
1,770
369
3,583
210

Hays

602

8,563

602

8,563

602

8,563

602

8,563

602

8,563

602

8,563

MODELED AVAILABLE GROUNDWATER FOR THE SALINE PORTION OF THE EDWARDS (BALCONES FAULT ZONE) AQUIFER INGROUNDWATER MANAGEMENT AREA 10 SUMMARIZED BY COUNTY, REGIONAL WATER PLANNING AREA (RWPA), AND RIVER
BASIN FOR EACH DECADE BETWEEN 2020 AND 2070. VALUES ARE IN ACRE-FEET PER YEARCountyCaldwell
Hays
Travis

RWPA
L

K
L

K

Total

River Basin

2020

2030

2040

2050

2060

2070

Colorado

469

469

469

469

469

469

Guadalupe

1,707

1,707

1,707

1,707

1,707

1,707

Guadalupe

280

280

280

280

280

280

Guadalupe
Colorado
Colorado

968
66

5,073

8,563

968
66

5,073

8,563

968
66

5,073

8,563

968
66

5,073

8,563

968
66

5,073

8,563

968
66

5,073

8,563

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 25 of 32

TABLE 7.

INPUTS TO CALULATE MODELED AVAILABLE GROUNDWATER FOR THE TRINITY AQUIFER INGROUNDWATER MANAGEMENT AREA 10, SUMMARIZED BY MAP AREA REPRESENTING EACHGROUNDWATER CONSERVATION DISTRICT (GCD), COUNTY, RIVER BASIN, AND REGIONAL WATERPLANNING AREA (RWPA) COMBINATIONS. AREA VALUES ARE IN ACRES, AND OTHER VALUES ARE IN
ACRE-FEET PER YEAR.

ArealextentEstimatedannualeffective
recharge

Estimatedannuallateralinflow

Estimatedannualvolumefromwaterlevel
declineModeledavailable
groundwater

Map
area1,2,3

GCD

County

River
Basin

RWPG

1

UvaldeCountyUWCDUvaldeNueces

L

372

36

4

0

40

L

N/A

N/A

N/A

N/A

N/A

L

1,282

149

318

32

499

2
3
4
5
6

7

8
9
10
11
12

Medina GCD
No GCD

Comal Trinity
GCD
Comal Trinity
GCD
BartonSprings/
Edwards
Aquifer
Conservation
District
BartonSprings/
Edwards
Aquifer
Conservation
District
BartonSprings/
Edwards
Aquifer
Conservation
DistrictSouthwestern
TravisCounty GCD
UvaldeCountyUWCDMedina GCD
Medina GCD

Medina
Bexar

Comal

San
AntonioSan
AntonioSan
Antonio

L
L

1

594

0

67

0

147

0

15

0

229

Comal

Guadalupe

Hays

Guadalupe

L

505

61

13

13

87

Hays

Colorado

K

494

57

12

12

81

TravisColorado

K

3

0

0

0

0

TravisColorado

K

11

1

0

0

1

UvaldeNuecesL

63,464

N/A

755

0

755

98,983

N/A

MedinaMedinaNuecesSan
AntonioLL

459,975

N/A

1. Map areas 1-10 represent outcrop areas and were assumed to be under unconfined aquifer conditions.
2. Map areas 11-31 represent subcrop areas and were assumed to be under confined aquifer conditions.

5,470
1,177

12

2

3. Map areas 24-26 cover the Barton Springs/Edwards Aquifer Conservation District and Plum Creek Conservation District where the two districts overlap.
These values are assigned to the Barton Springs/Edwards Aquifer Conservation District.

5,482
1,179

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 26 of 32

Table 7 (Continued)

Map
area1,2,3

GCD

County13

No GCD

Bexar

14
15
16
17
18
19
20

21

22
23

Comal
Trinity GCD
No GCD

No GCD
Comal
Trinity GCD
BartonSprings/
Edwards
Aquifer
Conservation
District
No GCD
BartonSprings/
Edwards
Aquifer
Conservation
District
BartonSprings/
Edwards
Aquifer
Conservation
District
BartonSprings/
Edwards
Aquifer
Conservation
District
Plum Creek
CD

River
basin

GuadalupeSan
AntonioSan
AntonioSan
Antonio
Guadalupe

Hays

Comal

Guadalupe
Comal

Guadalupe

RWPG

L

Modeledavailable
groundwater

N/A

N/A

N/A

472

0

Areal
extentEstimatedannuallateralinflow

N/A

N/A

1,907

N/A

L

9,243

L

757

L

Estimatedannualvolumefromwaterlevel
declineEstimatedannualeffective
rechargeL123,232

Guadalupe

L

CaldwellGuadalupe

Hays

N/A

2,290

N/A

188

N/A

30,533104,045

N/A

L

420

ColoradoK

Hays

Guadalupe

Hays
Hays

0

2,290

0

188

472

3

30,536

2,597

3

2,600

N/A

10

0

10

36,033

N/A

899

0

899

K

354

N/A

9

0

9

Colorado

L

1,286

N/A

32

0

32

Guadalupe

L

9,934

N/A

248

0

248

1. Map areas 1-10 represent outcrop areas and were assumed to be under unconfined aquifer conditions.
2. Map areas 11-31 represent subcrop areas and were assumed to be under confined aquifer conditions.

3. Map areas 24-26 cover the Barton Springs/Edwards Aquifer Conservation District and Plum Creek Conservation District where the two districts overlap.
These values are assigned to the Barton Springs/Edwards Aquifer Conservation District.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 27 of 32

Table 7 (Continued)

Map
area1,2,3

24

25

26
27
28
29

30
31

GCD

BartonSprings/
Edwards
Aquifer
Conservation
District3
BartonSprings/
Edwards
Aquifer
Conservation
District3
BartonSprings/
Edwards
Aquifer
Conservation
District3
Plum Creek
CD
Southwestern
Travis County
GCD
BartonSprings/
Edwards
Aquifer
Conservation
District
BartonSprings/
Edwards
Aquifer
Conservation
District
No GCD

Areal
extentEstimatedannualeffective
recharge

Estimatedannuallateralinflow

Estimatedannualvolumefromwaterlevel
declineModeledavailable
groundwaterCounty

River
basin

RWPG

Hays

Guadalupe

K

17

N/A

0

0

0

Hays

Colorado

K

1

N/A

0

0

0

Hays

Guadalupe

L

5,864

N/A

146

0

146

Hays

Guadalupe
Colorado

L

K

1,108

N/A

28

0

28

TravisColoradoK55,223

N/A

339

0

339

TravisGuadalupe

K

396

N/A

2

0

2

TravisColoradoK53,547

N/A

329

0

329

Travis18

N/A

1. Map areas 1-10 represent outcrop areas and were assumed to be under unconfined aquifer conditions.
2. Map areas 11-31 represent subcrop areas and were assumed to be under confined aquifer conditions.

0

0

0

3. Map areas 24-26 cover the Barton Springs/Edwards Aquifer Conservation District and Plum Creek Conservation District where the two districts overlap.
These values are assigned to the Barton Springs/Edwards Aquifer Conservation District.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 28 of 32

TABLE 8.

MODELED AVAILABLE GROUNDWATER FOR THE TRINITY AQUIFER IN GROUNDWATER MANAGEMENTAREA 10 SUMMARIZED BY GROUNDWATER CONSERVATION DISTRICT (GCD) AND COUNTY FOR EACH
DECADE BETWEEN 2010 AND 2060. VALUES ARE IN ACRE-FEET PER YEAR.

Groundwater Conservation
District
Barton Springs/ Edwards
Aquifer Conservation District
Comal Trinity GCD
Medina County GCD
Non-District Areas

2010

2020

2030

2040

2050

2060

Hays
TravisComal
MedinaCaldwellGuadalupe

3,854
341
33,554
6,661
10

3,854
341
33,554
6,661
10

3,854
341
33,554
6,661
10

3,854
341
33,554
6,661
10

3,854
341
33,554
6,661
10

3,854
341
33,554
6,661
10

276

276

276

276

276

276

TravisPlum Creek
Conservation District
Southwestern Travis
County GCD
Uvalde County UWCD
Total
TABLE 9.

CountyHays

TravisUvalde

660
329

1
795
46,481

660
329

1
795
46,481

660
329

1
795
46,481

660
329

1
795
46,481

660
329

1
795
46,481

660
329

1
795
46,481

MODELED AVAILABLE GROUNDWATER FOR THE TRINITY AQUIFER IN GROUNDWATER MANAGEMENTAREA 10 SUMMARIZED BY COUNTY, REGIONAL WATER PLANNING AREA (RWPA), AND RIVER BASIN
FOR EACH DECADE BETWEEN 2020 AND 2070. VALUES ARE IN ACRE-FEET PER YEAR.
CountyRWPA

River Basin

2020

2030

2040

2050

2060

2070

CaldwellL

GuadalupeL

Guadalupe
Guadalupe
San Antonio
Guadalupe
San Antonio
Colorado

10
31,035
2,519
188
472
980

10
31,035
2,519
188
472
980

10
31,035
2,519
188
472
980

10
31,035
2,519
188
472
980

10
31,035
2,519
188
472
980

10
31,035
2,519
188
472
980

Guadalupe
Nueces

2
795

2
795

2
795

2
795

2
795

2
795

Comal

Hays
MedinaTravisUvalde

L

K
L
L

K
L

Guadalupe
Colorado
Guadalupe
NuecesSan Antonio
Colorado

9
32
3,109
5,482
1,179
669

9
32
3,109
5,482
1,179
669

9
32
3,109
5,482
1,179
669

9
32
3,109
5,482
1,179
669

9
32
3,109
5,482
1,179
669

9
32
3,109
5,482
1,179
669

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 29 of 32

LIMITATIONS:

The groundwater model used in completing this analysis is the best available scientific toolthat can be used to meet the stated objectives. To the extent that this analysis will be used
for planning purposes and/or regulatory purposes related to pumping in the past and into
the future, it is important to recognize the assumptions and limitations associated with theuse of the results. In reviewing the use of models in environmental regulatory decision
making, the National Research Council (2007) noted:“Models will always be constrained by computational limitations, assumptions, andknowledge gaps. They can best be viewed as tools to help inform decisions rather
than as machines to generate truth or make decisions. Scientific advances will
never make it possible to build a perfect model that accounts for every aspect ofreality or to prove that a given model is correct in all respects for a particularregulatory application. These characteristics make evaluation of a regulatorymodel more complex than solely a comparison of measurement data with model
results.”

A key aspect of using the groundwater model to evaluate historical groundwater flow
conditions includes the assumptions about the location in the aquifer where historical
pumping was placed. Understanding the amount and location of historical pumping is as
important as evaluating the volume of groundwater flow into and out of the district,between aquifers within the district (as applicable), interactions with surface water (asapplicable), recharge to the aquifer system (as applicable), and other metrics that describe
the impacts of that pumping. In addition, assumptions regarding precipitation, recharge,
and streamflow are specific to a particular historical time period.

Because the application of the groundwater model was designed to address regional scalequestions, the results are most effective on a regional scale. The TWDB makes nowarranties or representations relating to the actual conditions of any aquifer at a particularlocation or at a particular time.
It is important for groundwater conservation districts to monitor groundwater pumping
and groundwater levels in the aquifer. Because of the limitations of the groundwater modeland the assumptions in this analysis, it is important that the groundwater conservation
districts work with the TWDB to refine this analysis in the future given the reality of how
the aquifer responds to the actual amount and location of pumping now and in the future.
Historical precipitation patterns also need to be placed in context as future climaticconditions, such as dry and wet year precipitation patterns, may differ and affectgroundwater flow conditions.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 30 of 32

REFERENCES:

Ashworth, J. B., 1983, Ground-water availability of the Lower Cretaceous formations in the
Hill Country of south-central Texas: Texas Department of Water Resources Report273, 173 p.

Bradley, R. G., 2011, GTA Aquifer Assessment 10-35 MAG, Northern saline Edwards Aquifer
Modeled Available Groundwater Estimates, Texas Water Development Board, 13 p.
http://www.twdb.texas.gov/groundwater/docs/AA/AA10-35_MAG.pdf

Bradley, R. G., 2013, Aquifer Assessment 10-28 MAG: Aquifer Assessment for the Leona
Gravel Aquifer Within Uvalde County in Groundwater Management Area 10, Texas
Water Development Board, 13 p.
http://www.twdb.texas.gov/groundwater/docs/AA/AA10-28_MAG.pdf
Cleaveland, M.K., 2006, Extended chronology of drought in the San Antonio area, revised
report: University of Arkansas, 29 p.
http://www.gbra.org/Documents/Reports/TreeRingStudy.pdf
Freeze, A.R. and Cherry, J.A., 1979, Groundwater, Prentice-Hall, 604 p.

George, P., 2010, GTA Aquifer Assessment 09-01: Texas Water Development Board, 14 p.
http://www.twdb.texas.gov/groundwater/docs/AA/AA09-01.pdf

Green, R.T, Winterle, J.R., and Prikryl, J.D., 2008, Discharge from the Edwards Aquifer
through the Leona River floodplain, Uvalde, Texas: Journal of the American Water
Resources Association, v. 44, No. 4, pp. 887-901.

Green, R.T., Bertetti, F.P., and McGinnis, R., 2009, Analysis of the Water Resources of the
Area Centered Within and Near Uvalde and Zavala Counties and Review of a Reporton a Potential Well Field and Pipeline in Uvalde County, Texas: SwRI Project No. 2014842, 53 p.
Harbaugh, A. W., 2009, Zonebudget Version 3.01, A computer program for computing
subregional water budgets for MODFLOW ground-water flow models, U.S.
Geological Survey Groundwater Software.

Harbaugh, A.W., Banta, E.R., Hill, M.C., and McDonald, M.G., 2000, MODFLOW-2000, The U.S.
Geological Survey modular ground-water model-User guide to modularization
concepts and the ground-water flow process: U.S. Geological Survey, Open-File
Report 00-92.
Hunt, B.B, 2017, Refining the northern Saline Edwards Aquifer desired future condition,
northern subdivision of GMA-10, Hays and Travis counties, Texas, Barton Springs
Edwards Aquifer Conservation District, Technical Memo 2017-1221, 2p.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 31 of 32

Hunt, B.B., Smith, B.A., Kromann, J.,Wierman, D.A., and Mikels, J.K., 2010, Compilation ofpumping tests in Travis and Hays counties, central Texas: Barton Springs/Edwards
Aquifer Conservation District Data Series Report 2010-0701, 12p.
Hunt, B.B., Smith, B.A., Holland, W.F., 2011, Technical Note 2011-0707: Information in
Support of the Drought DFC and Drought MAG, Barton Springs Segment of the
Edwards Aquifer, Barton Springs/Edwards Aquifer Conservation District, 5 p.

Hutchison, W. R., 2011, Draft GAM Task 10-027 (revised): Texas Water Development
Board, 8 p. http://www.twdb.texas.gov/groundwater/docs/GAMruns/Task10027revised_draft.pdf

Hutchison, W.R., 2010, GAM Task 10-005, Texas Water Development Board, 27p.
http://www.twdb.texas.gov/groundwater/docs/GAMruns/Task10-005.pdf

Hutchison, W.R. and Hill, M., 2011a, Report: Recalibration of the Edwards (Balcones Fault
Zone) Aquifer—Barton Springs Segment—Groundwater Flow Model, Texas Water
Development Board, 115.p.
http://www.twdb.texas.gov/groundwater/models/alt/ebfz_b/EBFZ_B_Model_Recal
ibration_Report.pdf
Hutchison, W.R. and Hill, M.E., 2011b, GAM Run 09-019: Groundwater Model Runs to
Estimate Monthly Average Discharge from Barton Springs under Alternative
Pumping Scenarios and Alternative Initial Conditions, June 1, 2011, 29 p.

Hutchison, W.R. and Oliver, W., 2011, GAM Run 10-058 MAG Version 2: Groundwater
Management Area 10 Model Runs to Estimate Springflow Under Assumed Future
Pumping and Recharge Conditions for the Northern Subdivision of the Edwards(Balcones Fault Zone) Aquifer, Texas Water Development Board, 17.p.
http://www.twdb.texas.gov/groundwater/docs/GAMruns/GR10-059_MAG_v2.pdf

Hutchison, W.R., Shi, J, and Jigmond, M, 2011, Groundwater Flow Model of The Kinney
County Area, Texas Water Development Board, 219 p.
http://www.twdb.texas.gov/groundwater/models/alt/knny/Kinney_County_Model_Report.pdf
Jones, I. C., Anaya, R., and Wade, S., 2009, Groundwater availability model for the Hill
Country portion of the Trinity Aquifer system, Texas, Texas Water Development
Board updated Trinity Hill Country GAM, 194 p.

Narasimhan, B., Srinvasan, R., Quiring, S., and Nielsen-Gammon, J.W., 2008, Digital Climatic
Atlas of Texas: Texas A&M University, Texas Water Development Board contract,
Report 2005-483-5591, 108 p.

GAM Run 16-033 MAG: Modeled Available Groundwater Aquifers in Groundwater Management Area 10
July 20, 2018
Page 32 of 32

National Research Council, 2007, Models in Environmental Regulatory Decision Making
Committee on Models in the Regulatory Decision Process, National Academies Press,
Washington D.C., 287 p., http://www.nap.edu/catalog.php?record_id=11972.
Shi, J, 2012, GAM Run 12-002 MAG: Modeled Available Groundwater for the Edwards(Balcones Fault Zone) Aquifer in Groundwater Management Area 10 for Kinney
County, Texas Water Development Board, 9 p.
http://www.twdb.texas.gov/groundwater/docs/GAMruns/GR12-002_MAG.pdf

Texas Water Code, 2017, http://www.statutes.legis.state.tx.us/docs/WA/pdf/WA.36.pdf.
Thorkildsen, D. and Backhouse, S., 2010, GTA Aquifer Assessment 10-06: Groundwater
Management Area 10 Trinity Aquifer Draft Managed Available Groundwater
estimates, Texas Water Development Board, 20 p.
http://www.twdb.texas.gov/groundwater/docs/AA/AA10-06.pdf

Thorkildsen, D. and Backhouse, S., 2011a, GTA Aquifer Assessment 10-26, Austin Chalk
Aquifer Managed Available Groundwater Estimates, Texas Water Development
Board 11 p. http://www.twdb.texas.gov/groundwater/docs/AA/AA10-26_MAG.pdf
Thorkildsen, D. and Backhouse, S., 2011b, GTA Aquifer Assessment 10-27, Buda Limestone
Aquifer Managed Available Groundwater Estimates, Texas Water Development
Board 10 p. http://www.twdb.texas.gov/groundwater/docs/AA/AA10-27_MAG.pdf

GAM RUN 17-027 MAG:This page is intentionally left blank.

GAM RUN 17-027 MAG:
MODELED AVAILABLE GROUNDWATER FOR THE
CARRIZO-WILCOX, QUEEN CITY, SPARTA, ANDYEGUA-JACKSON AQUIFERS INGROUNDWATER MANAGEMENT AREA 13
Shirley C. Wade, Ph.D., P.G.
Texas Water Development Board
Groundwater Division
Groundwater Availability Modeling Department(512) 936-0883
October 27, 2017

EXECUTIVE SUMMARY:
The modeled available groundwater for Groundwater Management Area 13 for the CarrizoWilcox, Queen City, Sparta, and Yegua-Jackson aquifers is summarized by decade for the
groundwater conservation districts (Tables 1 through 4 respectively) and for use in theregional water planning process (Tables 5 through 8 respectively). The modeled available
groundwater estimates for the Carrizo-Wilcox Aquifer range from approximately 626,000
acre-feet per year in 2012 to approximately 589,000 acre-feet per year in 2070 (Table 1).
The modeled available groundwater estimates for the Queen City Aquifer range fromapproximately 19,000 acre-feet per year in 2012 to approximately 15,000 acre-feet per
year in 2070 (Table 2). The modeled available groundwater estimates for the Sparta
Aquifer range from approximately 7,000 acre-feet per year in 2012 to approximately 6,000
acre-feet per year in 2070 (Table 3). The estimates were extracted from results of a model
run using the groundwater availability model for the southern part of the Carrizo-Wilcox,
Queen City, and Sparta aquifers (version 2.01). The model run files, which meet thesecondary desired future condition adopted by district representatives of Groundwater
Management Area 13 for the Carrizo-Wilcox, Queen City, and Sparta Aquifers, were
submitted to the Texas Water Development Board (TWDB) on February 28, 2017, as part of
the Desired Future Conditions Explanatory Report for Groundwater Management Area 13.
The modeled available groundwater estimates for the Yegua-Jackson Aquifer areapproximately 7,000 acre-feet per year from 2010 to 2070 (Table 4). The estimates wereextracted from results of a model run using the groundwater availability model for theGAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 4 of 36

Yegua-Jackson Aquifer version 1.01. The model run files, which meet the desired future
conditions adopted by district representatives of Groundwater Management Area 13 forthe Yegua-Jackson Aquifer, were submitted to the TWDB on March 29, 2017 as
supplemental information for the original February 28, 2017 submittal. The explanatory
reports and other materials submitted to the TWDB were determined to beadministratively complete on September 8, 2017.

REQUESTOR:
Mr. Greg Sengelmann, coordinator of Groundwater Management Area 13.

DESCRIPTION OF REQUEST:In a letter dated February 24, 2017, Dr. William R. Hutchison, on behalf of Groundwater
Management Area 13, provided the TWDB with the desired future conditions of the
Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers adopted by thegroundwater conservation districts in Groundwater Management Area 13. The desired
future conditions for the Carrizo-Wilcox, Queen City, and Sparta aquifers described in
Resolution 16-01 from Groundwater Management Area 13, adopted November 21, 2016are:“The first proposed desired future condition for the Carrizo-Wilcox, Queen City andSparta aquifers in Groundwater Management Area 13 is that 75 percent of thesaturated thickness in the outcrop at the end of 2012 remains in 2070. This desired
future condition is considered feasible despite model predictions to the contrary as
detailed in GMA 13 Technical Memorandum 16-08”, and

“In addition, a secondary proposed desired future condition for the Carrizo-Wilcox,
Queen City, and Sparta aquifers in Groundwater Management Area 13 is an averagedrawdown of 48 feet for all of GMA 13. The drawdown is calculated from the end of2012 conditions to the year 2070. This desired future condition is consistent with
Scenario 9 as detailed in GMA 13 Technical Memorandum 16-01 and GMA 13
Technical Memorandum 16-08.”

The desired future conditions for the Yegua-Jackson Aquifer described in Resolution 16-02
from Groundwater Management Area 13, adopted November 21, 2016 are:“For Gonzales County, the average drawdown from 2010 to 2070 is 3 feet

For Karnes County, the average drawdown from 2010 to 2070 is 1 foot

For all other counties in GMA 13, the Yegua-Jackson is classified as not relevant for
purposes of joint planning.”

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 5 of 36

TWDB staff reviewed the model files associated with the desired future conditions andreceived clarification on procedures and assumptions from the Groundwater Management
Area 13 Technical Coordinator on April 4, 2017, and on September 21, 2017. Groundwater
Management Area 13 adopted two desired future conditions for the Carrizo-Wilcox, Queen
City, and Sparta Aquifers and they were not mutually compatible in the groundwater
availability model. The technical coordinator for the groundwater management area
confirmed that their intention was for the modeled available groundwater values to be
based on the secondary desired future condition and Pumping Scenario 9 (Hutchison,
2017a). The first proposed desired future condition was not intended for the calculation ofmodeled available groundwater. Other questions included whether drawdown averages
and modeled available groundwater values were based on official aquifer extent or model
extent, whether to include dry cells in drawdown averaging, which stress periods to use fordrawdown calculation, and whether to provide modeled available groundwater separately
for the Carrizo-Wilcox, Queen City, and Sparta aquifers or as a combined value for all threeaquifers .
In addition, TWDB staff requested and received supplemental model files for the YeguaJackson Aquifer on March 29, 2017, and supplemental documentation (Hutchison, 2017d)
related to initial conditions for modeling the Carrizo-Wilcox, Queen City, and Sparta
aquifers from Dr. William R. Hutchison on August 25, 2017, on behalf of Groundwater
Management Area 13. All clarifications are included in the Parameters and Assumptions
Section of this report.

METHODS:
The groundwater availability model for the southern part of the Carrizo-Wilcox, Queen
City, and Sparta aquifers (Figures 1 through 4) was run using the model files submittedwith the explanatory reports (Hutchison, 2017c). Model-calculated drawdowns wereextracted for the year 2070. An overall drawdown average was calculated for the entire
Groundwater Management Area 13 using all aquifer layers in the average. Based on
clarifications, the reference year for drawdown calculations was the end of 2011 (or the
beginning of 2012). As specified in the clarifications, drawdowns for cells that became dry
during the simulation (water level dropped below the base of the cell) were excluded fromthe averaging. The calculated drawdown average was compared with the desired future
condition of 48 feet to verify that the pumping scenario (Hutchison, 2017a) achieved thedesired future conditions within one foot.
The groundwater availability model for the Yegua-Jackson Aquifer (Figures 5 and 6) was
run using the model files submitted on March 29, 2017, as supplemental information anddrawdowns were calculated for the year 2070. County-wide average drawdowns were

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 6 of 36

calculated for Gonzales and Karnes counties within Groundwater Management Area 13
using all model layers in the average. Based on clarifications, the reference year for
drawdown calculation was the end of 2009 (or the beginning of 2010). As specified in theclarifications, drawdowns for cells that became dry during the simulation (water level
dropped below the base of the cell) were excluded from the averaging. The calculated
drawdown averages were compared with the desired future conditions for Gonzales andKarnes counties to verify that the pumping scenario (Hutchison, 2017b) achieved thedesired future conditions within one foot.
The modeled available groundwater values were determined by extracting pumping rates
by decade from the model results using ZONEBUDGET Version 3.01 (Harbaugh, 2009).
Annual pumping rates by aquifer are presented by county and groundwater conservation
district, subtotaled by groundwater conservation district, and then summed for
Groundwater Management Area 13 (Tables 1 through 4). Annual pumping rates by aquifer
are also presented by county, river basin, and regional water planning area within
Groundwater Management Area 13 (Tables 5 through 8). Additional tables are provided inAppendix A which summarize the total modeled available groundwater for the CarrizoWilcox, Queen City, and Sparta aquifers by regional water planning area, county, river
basin, and groundwater conservation district. Tables are provided in Appendix B which
split the Carrizo-Wilcox, Queen City, and Sparta aquifers modeled pumping by model layer
for each groundwater conservation district.
Modeled Available Groundwater and Permitting
As defined in Chapter 36 of the Texas Water Code (2011), “modeled available
groundwater” is the estimated average amount of water that may be produced annually toachieve a desired future condition. Groundwater conservation districts are required toconsider modeled available groundwater, along with several other factors, when issuing
permits in order to manage groundwater production to achieve the desired future
condition(s). The other factors districts must consider include annual precipitation andproduction patterns, the estimated amount of pumping exempt from permitting, existing
permits, and a reasonable estimate of actual groundwater production under existing
permits.

PARAMETERS AND ASSUMPTIONS:The parameters and assumptions for the modeled available groundwater estimates aredescribed below:

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 7 of 36

Carrizo-Wilcox, Queen City, and Sparta aquifers

We used Version 2.01 of the groundwater availability model for the southern part of
the Carrizo-Wilcox, Queen City, and Sparta aquifers. See Deeds and others (2003)
and Kelley and others (2004) for assumptions and limitations of the groundwater
availability model for the southern part of the Carrizo-Wilcox, Queen City, andSparta aquifers.

This groundwater availability model includes eight layers, which generally
represent the Sparta Aquifer (Layer 1), the Weches Confining Unit (Layer 2), theQueen City Aquifer (Layer 3), the Reklaw Confining Unit (Layer 4), the Carrizo(Layer 5), the Upper Wilcox (Layer 6), the Middle Wilcox (Layer 7), and the Lower
Wilcox (Layer 8). Parts of the Upper Wilcox do not exist in Groundwater
Management Area 13 and the official extent of the Queen City and Sparta aquifers
end around the Frio River. Layers represent equivalent geologic units outside of theofficial aquifer extents.



The model was run with MODFLOW-96 (Harbaugh and others, 1996).

The end of the calibration period was extended from 1999 to 2011 (Hutchison,
2017e) and the reference year for drawdown calculations was the end of 2011.



Drawdown averages and modeled available groundwater values were based on theextent of the model area rather than the official aquifer boundaries.



Drawdowns for cells where water levels dropped below the base elevation of thecell causing the cell to become inactive (dry cells) were excluded from the averaging.

A tolerance of one foot was assumed when comparing desired future conditions(Table 1, average drawdown values per county) to model drawdown results.



Estimates of modeled available groundwater from the model simulation wererounded to whole numbers.



Although the desired future condition for the Carrizo-Wilcox, Queen City, and Sparta
aquifers is a combined value for all three aquifers, the modeled available
groundwater values will be provided individually for each aquifer per clarificationfrom the Groundwater Management Area 13 Technical Coordinator on September
21, 2017.

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 8 of 36

Yegua-Jackson AquiferWe used version 1.01 of the groundwater availability model for the Yegua-Jackson
Aquifer. See Deeds and others (2010) for assumptions and limitations of thegroundwater availability model.

This groundwater availability model includes five layers which represent theoutcrop of the Yegua-Jackson Aquifer and younger overlying units—the Catahoula
Formation (Layer 1), the upper portion of the Jackson Group (Layer 2), the lower
portion of the Jackson Group (Layer 3), the upper portion of the Yegua Group (Layer4), and the lower portion of the Yegua Group (Layer 5).



The model was run with MODFLOW-2000 (Harbaugh and others, 2000).



The end of the calibration period was extended from 1997 to 2009 (Oliver, 2010)
and the reference year for drawdown calculations was the end of 2009.



Drawdown averages and modeled available groundwater values were based on theextent of the model area rather than the official aquifer boundaries.



Drawdown for cells where water levels dropped below the base elevation of the cellcausing the cell to become inactive (dry cells) were excluded from the averaging.

A tolerance of one foot was assumed when comparing desired future conditions(Table 1, average drawdown values per county) to model drawdown results.



Estimates of modeled available groundwater from the model simulation wererounded to whole numbers.

RESULTS:
The modeled available groundwater estimates for the Carrizo-Wilcox Aquifer range fromapproximately 626,000 acre-feet per year in 2012 to approximately 589,000 acre-feet per
year in 2070 (Table 1). The modeled available groundwater estimates for the Queen City
Aquifer range from approximately 19,000 acre-feet per year in 2012 to approximately
15,000 acre-feet per year in 2070 (Table 2). The modeled available groundwater estimate
for the Sparta Aquifer ranges from approximately 7,000 acre-feet per year in 2012 toapproximately 6,000 acre-feet per year in 2070 (Table 3). The modeled available
groundwater is summarized by groundwater conservation district and county for the
Carrizo-Wilcox, Queen City, and Sparta aquifers (Tables 1, 2, and 3 respectively). The
modeled available groundwater has also been summarized by county, river basin, andregional water planning area for use in the regional water planning process for the CarrizoWilcox, Queen City, and Sparta aquifers (Tables 5, 6, and 7 respectively). Small differences

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 9 of 36

in values between table summaries are due to rounding. Additional tables are provided inAppendix A which summarize the total modeled available groundwater for all threeaquifers by regional water planning area, county, river basin, and groundwater
conservation district. Tables are provided in Appendix B which split the modeled pumping
by each model aquifer layer for each groundwater conservation district.
The modeled available groundwater estimate for the Yegua-Jackson Aquifer isapproximately 7,000 acre-feet per year from 2010 to 2070 (Table 4). The modeled
available groundwater for the Yegua-Jackson Aquifer is summarized by groundwater
conservation district and county (Table 4) and by county, river basin, and regional waterplanning area for use in the regional water planning process (Table 8). Small differences ofvalues between table summaries are due to rounding.

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 10 of 36

FIGURE 1.

GROUNDWATER MANAGEMENT AREA (GMA) 13 BOUNDARY, RIVER BASINS, AND
COUNTIES OVERLAIN ON THE EXTENT OF THE CARRIZO-WILCOX AQUIFER IN THE
GROUNDWATER AVAILABILITY MODEL FOR THE SOUTHERN PORTION OF THE
CARRIZO-WILCOX, QUEEN CITY, AND SPARTA AQUIFERS.

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 11 of 36

FIGURE 2.

REGIONAL WATER PLANNING AREAS (RWPAS), RIVER BASINS, GROUNDWATERCONSERVATION DISTRICTS (GCDS), AND COUNTIES OVERLAIN ON THE EXTENT OF
THE CARRIZO-WILCOX AQUIFER IN THE GROUNDWATER AVAILABILITY MODEL FOR
THE SOUTHERN PORTION OF THE CARRIZO-WILCOX, QUEEN CITY, AND SPARTAAQUIFERS.

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 12 of 36

FIGURE 3.

REGIONAL WATER PLANNING AREAS (RWPAS), RIVER BASINS, GROUNDWATERCONSERVATION DISTRICTS (GCDS), AND COUNTIES OVERLAIN ON THE EXTENT OF
THE QUEEN CITY AQUIFER IN THE GROUNDWATER AVAILABILITY MODEL FOR THE
SOUTHERN PORTION OF THE CARRIZO-WILCOX, QUEEN CITY, AND SPARTA AQUIFERS.

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 13 of 36

FIGURE 4.

REGIONAL WATER PLANNING AREAS (RWPAS), RIVER BASINS, GROUNDWATERCONSERVATION DISTRICTS (GCDS), AND COUNTIES OVERLAIN ON THE EXTENT OF
THE SPARTA AQUIFER IN THE GROUNDWATER AVAILABILITY MODEL FOR THE
SOUTHERN PORTION OF THE CARRIZO-WILCOX, QUEEN CITY, AND SPARTA AQUIFERS.

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 14 of 36

FIGURE 5.

GROUNDWATER MANAGEMENT AREA (GMA) 13 BOUNDARY, RIVER BASINS, AND
COUNTIES OVERLAIN ON THE EXTENT OF THE YEGUA-JACKSON AQUIFER IN THE
GROUNDWATER AVAILABILITY MODEL.

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 15 of 36

FIGURE 6.

REGIONAL WATER PLANNING AREAS (RWPAS), RIVER BASINS, GROUNDWATERCONSERVATION DISTRICTS (GCDS), AND COUNTIES OVERLAIN ON THE EXTENT OF
THE YEGUA-JACKSON AQUIFER IN THE GROUNDWATER AVAILABILITY MODEL.

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers in Groundwater
Management Area 13
October 27, 2017
Page 16 of 36
TABLE 1.

MODELED AVAILABLE GROUNDWATER FOR THE CARRIZO-WILCOX AQUIFER IN GROUNDWATER MANAGEMENT AREA 13
SUMMARIZED BY GROUNDWATER CONSERVATION DISTRICT (GCD) AND COUNTY FOR EACH DECADE BETWEEN 2012 AND
2070. VALUES ARE IN ACRE-FEET PER YEAR.

Groundwater
Conservation
District

CountyAquifer

2012

2020

2030

2040

2050

2060

2070

Evergreen UWCD
Evergreen UWCD
Evergreen UWCD

Atascosa
Frio
KarnesCarrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox

67,668111,920
1,042

67,668111,920
1,042

70,28685,036
1,085

71,06682,9991,146

72,71881,083
1,212

74,29879,1971,264

75,87477,353
1,296

Evergreen UWCD
Evergreen UWCD
Total
Gonzales County
UWCD
Gonzales County
UWCD
Gonzales County
UWCD Total
Guadalupe County
GCD
McMullen GCD
Medina County
GCD
Plum Creek CD
Uvalde County
UWCD

WilsonCarrizo-Wilcox

108,465

108,465

104,918

106,196

107,653

109,358

111,093

Carrizo-Wilcox

289,096

289,096

261,325

261,406

262,666

264,116

265,616

Caldwell

Carrizo-Wilcox

39,71339,71339,71336,67836,67833,64333,643

GonzalesCarrizo-Wilcox

81,594

81,594

81,59485,37185,73585,98785,996

Carrizo-Wilcox

121,307

121,307

121,307122,049

122,413

119,630

119,638

Guadalupe
McMullen

Carrizo-Wilcox
Carrizo-Wilcox

48,032
7,002

52,528
7,056

47,844
7,056

45,776
4,405

47,995
4,405

47,965
4,405

47,833
4,405

MedinaCaldwell

Carrizo-Wilcox
Carrizo-Wilcox

2,657
21,073

2,657
20,6102,648
20,6102,647
20,202

2,647
20,202

2,646
19,625

2,646
19,625

UvaldeCarrizo-Wilcox

4,451

2,975

1,231

828

828

828

828

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers in Groundwater
Management Area 13
October 27, 2017
Page 17 of 36

Groundwater
Conservation
District
Wintergarden GCD
Wintergarden GCD
Wintergarden GCD
Wintergarden
GCD Total
No District-County
No District-County
No District-County
No District-County
No District-County
No DistrictCounty Total
Total for GMA 13

CountyAquifer

2012

2020

2030

2040

2050

2060

2070

Dimmit
La Salle
ZavalaCarrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox

4,129
6,863
35,6534,129
6,863
35,6534,129
6,863
35,3054,129
6,863
35,171

4,129
6,863
35,071

4,129
6,863
34,7504,129
6,863
34,695Bexar
Caldwell
GonzalesMaverick
Webb

Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox

46,64581,992
921
59
2,203
916

46,645
81,474
921
59
2,042
916

46,29780,817
921
59
2,042
916

46,16380,348
921
59
2,001
916

46,06379,470
921
59
1,914
916

45,742
78,977
921
59
1,570
916

45,68778,807
921
59
1,531
916

Carrizo-Wilcox
Carrizo-Wilcox

86,091
626,354

85,412628,284

84,755593,072

84,245
587,722

83,280590,498

82,443
587,400

82,235588,514

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers in Groundwater
Management Area 13
October 27, 2017
Page 18 of 36
TABLE 2.

MODELED AVAILABLE GROUNDWATER FOR THE QUEEN CITY AQUIFER IN GROUNDWATER MANAGEMENT AREA 13
SUMMARIZED BY GROUNDWATER CONSERVATION DISTRICT (GCD) AND COUNTY FOR EACH DECADE BETWEEN 2012 AND
2070. VALUES ARE IN ACRE-FEET PER YEAR.

Groundwater
Conservation
District
Evergreen UWCD
Evergreen UWCD
Evergreen UWCD
Evergreen UWCD
Total
Gonzales County
UWCD
Gonzales County
UWCD
Gonzales County
UWCD Total
Guadalupe County
GCD
McMullen GCD
Plum Creek CD
Wintergarden
GCD
Total for GMA 13

County

2012

2020

2030

2050

2060

Queen City
Queen City
Queen City

4,075
6,759
2,780

4,075
6,759
2,780

4,543
4,745
1,508

4,543
4,573
1,339

4,513
4,429
1,191

4,407
4,257
1,059

4,302
4,113
945

Queen City

13,614

13,614

10,797

10,455

10,133

9,723

9,359

CaldwellQueen City

284

284

284

284

284

284

284

GonzalesQueen City

5,067

5,067

5,067

5,067

5,067

5,067

5,067

Queen City

5,351

5,351

5,351

5,351

5,351

5,351

5,351

Guadalupe
McMullen
CaldwellQueen City
Queen City
Queen City

0
134
22

0
134
22

0
134
22

0
134
22

0
134
22

0
134
22

0
134
22

La Salle

Queen City
Queen City

2
19,123

2
19,1232
16,3072
15,9652
15,643

2
15,233

2
14,869Atascosa
Frio
WilsonAquifer

2040

2070

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers in Groundwater
Management Area 13
October 27, 2017
Page 19 of 36
TABLE 3.

MODELED AVAILABLE GROUNDWATER FOR THE SPARTA AQUIFER IN GROUNDWATER MANAGEMENT AREA 13 SUMMARIZEDBY GROUNDWATER CONSERVATION DISTRICT (GCD) AND COUNTY FOR EACH DECADE BETWEEN 2012 AND 2070. VALUESARE IN ACRE-FEET PER YEAR.

Groundwater
Conservation District

CountyAquifer

2012

2020

2030

2040

2050

2060

2070

Evergreen UWCD

Atascosa

Sparta

1,219

1,215

1,188

1,129

1,083

1,044

1,013

Evergreen UWCD
Evergreen UWCD
Evergreen UWCD Total
Gonzales County UWCD
McMullen GCD
Wintergarden GCD
Total for GMA 13

Frio
WilsonSpartaSpartaSpartaSpartaSpartaSpartaSparta

1,045
462
2,726
3,554
89
983
7,353

1,045
462
2,723
3,554
89
983
7,349

728
251
2,166
3,554
89
983
6,793

702
224
2,056
3,554
89
983
6,682

674
198
1,955
3,554
89
983
6,582

651
176
1,870
3,554
89
983
6,497

624
156
1,792
3,554
89
983
6,419

TABLE 4.

GonzalesMcMullen
La Salle

MODELED AVAILABLE GROUNDWATER FOR THE YEGUA-JACKSON AQUIFER IN GROUNDWATER MANAGEMENT AREA 13
SUMMARIZED BY GROUNDWATER CONSERVATION DISTRICT (GCD) AND COUNTY FOR EACH DECADE BETWEEN 2010 AND
2070. VALUES ARE IN ACRE-FEET PER YEAR.

Groundwater
Conservation District
Evergreen UWCD
Gonzales County UWCDNo District-County
Total for GMA 13

CountyAquifer

2010

2020

2030

2040

2050

2060

2070

KarnesYegua-Jackson

2,059

2,059

2,059

2,059

2,059

2,059

2,059

GonzalesGonzalesYegua-Jackson
Yegua-Jackson
Yegua-Jackson

4,140
573
6,771

4,140
573
6,771

4,140
573
6,771

4,140
573
6,771

4,140
573
6,771

4,140
573
6,771

4,140
573
6,771

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers in Groundwater
Management Area 13
October 27, 2017
Page 20 of 36
TABLE 5.

CountyMODELED AVAILABLE GROUNDWATER BY DECADE FOR THE CARRIZO-WILCOX AQUIFER IN GROUNDWATER MANAGEMENTAREA 13. RESULTS ARE IN ACRE-FEET PER YEAR AND ARE SUMMARIZED BY COUNTY, REGIONAL WATER PLANNING AREA
(RWPA), RIVER BASIN, AND AQUIFER.

RWPAAtascosa

L

Atascosa
Bexar

L
L

Bexar
CaldwellCaldwellDimmitDimmitFrio
GonzalesGonzalesGuadalupe

L
L
L
L
L
L
L
L
L

Guadalupe
KarnesKarnes

L
L
L

Karnes
La Salle
MedinaL
L
L

MedinaUvaldeWilson

L
L
L

River
Basin
NuecesSan
Antonio
NuecesSan
Antonio
Colorado
Guadalupe
NuecesRio Grande
NuecesGuadalupe
LavacaGuadalupeSan
Antonio
Guadalupe
NuecesSan
Antonio
NuecesNuecesSan
Antonio
NuecesGuadalupe

Aquifer

2020

2030

2040

2050

2060

2070

Carrizo-Wilcox

67,54870,16670,946

72,59874,17875,754120
48,152120
48,152120
48,152120
48,152120
48,152

120
48,17633,322593
60,652
4,022
107
111,920
81,438215
36,18032,665593
60,652
4,022
107
85,03681,438215
32,15032,196593
57,2084,022
107
82,99985,216
215
29,76731,318593
57,2084,022
107
81,08385,579215
31,56930,825593
53,596
4,022
107
79,197
85,832
215
31,79330,631593
53,5964,022
107
77,35385,840215
31,744

16,347177
83

15,69318587

16,008195
92

16,426207
97

16,172
215
101

16,089
220
103

783
6,863
2,652

813
6,863
2,643

859
6,863
2,643

909
6,863
2,642

948
6,863
2,641

972
6,863
2,641

5
2,975
20,2875
1,231
20,186

5828
20,3405828
20,452

5828
20,783

5828
20,923Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers in Groundwater
Management Area 13
October 27, 2017
Page 21 of 36

CountyRWPA

WilsonL

WilsonZavalaMaverick
Maverick
Webb
Webb
McMullen
GMA 13 Total

L
L
M
M
M
M
N

River
Basin
NuecesSan
Antonio
NuecesNuecesRio Grande
NuecesRio Grande
NuecesAquifer

2020

2030

2040

2050

2060

Carrizo-Wilcox

7,652

7,154

7,317

7,510

7,709

7,938

80,526
77,57778,53879,69180,86535,65335,30535,17135,07134,750
777
777
777
777
472
1,265
1,265
1,224
1,137
1,097
92
92
92
92
92
824
824
824
824
824
7,056
7,056
4,405
4,405
4,405
628,284 593,072 587,722 590,498 587,400

82,232
34,695
472
1,059
92
824
4,405
588,514

Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox
Carrizo-Wilcox

2070

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers in Groundwater
Management Area 13
October 27, 2017
Page 22 of 36
TABLE 6.

CountyAtascosa
CaldwellFrio
GonzalesGonzalesGuadalupe
La Salle
WilsonWilsonWilsonMcMullen
GMA 13
Total

MODELED AVAILABLE GROUNDWATER BY DECADE FOR THE QUEEN CITY AQUIFER IN GROUNDWATER MANAGEMENT AREA
13. RESULTS ARE IN ACRE-FEET PER YEAR AND ARE SUMMARIZED BY COUNTY, REGIONAL WATER PLANNING AREA (RWPA),
RIVER BASIN, AND AQUIFER.

RWPA
L
L
L
L
L
L
L
L
L
L
N

River
Basin
NuecesGuadalupe
NuecesGuadalupe
LavacaGuadalupe
NuecesGuadalupe
NuecesSan Antonio
NuecesAquifer
Queen City
Queen City
Queen City
Queen City
Queen City
Queen City
Queen City
Queen City
Queen City
Queen City
Queen City
Queen City

2020

2030

2040

2050

2060

2070

4,075
307
6,759
5,032
35
0
2
236
273
2,271
134

4,543
307
4,745
5,032
35
0
2
128
148
1,232
134

4,543
307
4,573
5,032
35
0
2
114
132
1,094
134

4,513
307
4,429
5,032
35
0
2
101
117
973
134

4,407
307
4,257
5,032
35
0
2
90
104
865
134

4,302
307
4,113
5,032
35
0
2
80
93
772
134

19,123

16,307

15,965

15,643

15,233

14,869GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers in Groundwater
Management Area 13
October 27, 2017
Page 23 of 36
TABLE 7.

MODELED AVAILABLE GROUNDWATER BY DECADE FOR THE SPARTA AQUIFER IN GROUNDWATER MANAGEMENT AREA 13.
RESULTS ARE IN ACRE-FEET PER YEAR AND ARE SUMMARIZED BY COUNTY, REGIONAL WATER PLANNING AREA (RWPA),
RIVER BASIN, AND AQUIFER.

CountyAtascosa
Frio
GonzalesGonzales
La Salle
WilsonWilson

RWPA
L
L
L
L
L
L
L

WilsonL
McMullenN
GMA 13 Total

River
Basin
NuecesNuecesGuadalupe
LavacaNuecesGuadalupe
NuecesSan
Antonio
NuecesAquifer
SpartaSpartaSpartaSpartaSpartaSpartaSpartaSpartaSpartaSparta

2020

2030

2040

2050

2060

2070

1,215
1,045
3,531
23
983
42
102

1,188
728
3,531
23
983
23
55

1,129
702
3,531
23
983
20
49

1,083
674
3,531
23
983
18
44

1,044
651
3,531
23
983
16
39

1,013
624
3,531
23
983
14
34

319
89
7,349

173
89
6,793

154
89
6,682

137
89
6,582

121
89
6,497

108
89
6,419

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers in Groundwater
Management Area 13
October 27, 2017
Page 24 of 36
TABLE 8.

MODELED AVAILABLE GROUNDWATER BY DECADE FOR THE YEGUA-JACKSON AQUIFER IN GROUNDWATER MANAGEMENTAREA 13. RESULTS ARE IN ACRE-FEET PER YEAR AND ARE SUMMARIZED BY COUNTY, REGIONAL WATER PLANNING AREA
(RWPA), RIVER BASIN, AND AQUIFER.

CountyRWPAAtascosa
Frio
GonzalesGonzalesKarnesKarnes

L
L
L
L
L
L

Karnes
La Salle
WilsonWilson

L
L
L
L

WilsonWebb
Webb
ZapataMcMullen
GMA 13 Total

L
M
M
M
N

River
Basin
NuecesNuecesGuadalupe
LavacaGuadalupe
NuecesSan
Antonio
NuecesGuadalupe
NuecesSan
Antonio
NuecesRio Grande
Rio Grande
NuecesAquifer

2020

2030

2040

2050

2060

2070

Yegua-Jackson
Yegua-Jackson
Yegua-Jackson
Yegua-Jackson
Yegua-Jackson
Yegua-Jackson
Yegua-Jackson

NULL
NULL
4,694
19
327
91

NULL
NULL
4,694
19
327
91

NULL
NULL
4,694
19
327
91

NULL
NULL
4,694
19
327
91

NULL
NULL
4,694
19
327
91

NULL
NULL
4,694
19
327
91

1,641
NULL
NULL
NULL

1,641
NULL
NULL
NULL

1,641
NULL
NULL
NULL

1,641
NULL
NULL
NULL

1,641
NULL
NULL
NULL

1,641
NULL
NULL
NULL

NULL
NULL
NULL
NULL
NULL
6,771

NULL
NULL
NULL
NULL
NULL
6,771

NULL
NULL
NULL
NULL
NULL
6,771

NULL
NULL
NULL
NULL
NULL
6,771

NULL
NULL
NULL
NULL
NULL
6,771

NULL
NULL
NULL
NULL
NULL
6,771

Yegua-Jackson
Yegua-Jackson
Yegua-Jackson
Yegua-Jackson
Yegua-Jackson
Yegua-Jackson
Yegua-Jackson
Yegua-Jackson
Yegua-Jackson

NULL: Groundwater Management Area 13 declared the Yegua-Jackson Aquifer not relevant in these areas.

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 25 of 36

LIMITATIONS:
The groundwater model used in completing this analysis is the best available scientific toolthat can be used to meet the stated objectives. To the extent that this analysis will be used
for planning purposes and/or regulatory purposes related to pumping in the past and into
the future, it is important to recognize the assumptions and limitations associated with theuse of the results. In reviewing the use of models in environmental regulatory decision
making, the National Research Council (2007) noted:“Models will always be constrained by computational limitations, assumptions, andknowledge gaps. They can best be viewed as tools to help inform decisions rather
than as machines to generate truth or make decisions. Scientific advances will nevermake it possible to build a perfect model that accounts for every aspect of reality or
to prove that a given model is correct in all respects for a particular regulatory
application. These characteristics make evaluation of a regulatory model more
complex than solely a comparison of measurement data with model results.”
A key aspect of using the groundwater model to evaluate historic groundwater flow
conditions includes the assumptions about the location in the aquifer where historic
pumping was placed. Understanding the amount and location of historic pumping is as
important as evaluating the volume of groundwater flow into and out of the district,between aquifers within the district (as applicable), interactions with surface water (asapplicable), recharge to the aquifer system (as applicable), and other metrics that describe
the impacts of that pumping. In addition, assumptions regarding precipitation, recharge,
and streamflow are specific to a particular historic time period.
Because the application of the groundwater model was designed to address regional scalequestions, the results are most effective on a regional scale. The TWDB makes nowarranties or representations relating to the actual conditions of any aquifer at a particularlocation or at a particular time.
It is important for groundwater conservation districts to monitor groundwater pumping
and groundwater levels in the aquifer. Because of the limitations of the groundwater modeland the assumptions in this analysis, it is important that the groundwater conservation
districts work with the TWDB to refine this analysis in the future given the reality of how
the aquifer responds to the actual amount and location of pumping now and in the future.
Historic precipitation patterns also need to be placed in context as future climaticconditions, such as dry and wet year precipitation patterns, may differ and affectgroundwater flow conditions.

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 26 of 36

REFERENCES:
Deeds, N., Kelley, V., Fryar, D., Jones, T., Whallon, A.J., and Dean, K.E., 2003, Groundwater
Availability Model for the Southern Carrizo-Wilcox Aquifer: Contract report to the
Texas Water Development Board, 452 p.,
http://www.twdb.texas.gov/groundwater/models/gam/czwx_s/CZWX_S_Full_Repo
rt.pdf.
Deeds, N. E., Yan, T., Singh, A., Jones, T. L., Kelley, V. A., Knox, P. R., and Young, S. C., 2010,
Groundwater availability model for the Yegua-Jackson Aquifer: Final report
prepared for the Texas Water Development Board by INTERA, Inc., 582 p.,
http://www.twdb.texas.gov/groundwater/models/gam/ygjk/YGJK_Model_Report.p
df.
Harbaugh, A. W., 2009, Zonebudget Version 3.01, A computer program for computing
subregional water budgets for MODFLOW ground-water flow models, U.S.
Geological Survey Groundwater Software.
Harbaugh, A.W. and McDonald, M.G., 1996, User’s documentation for MODFLOW-96, an
update to the U.S. Geological Survey Modular Finite-Difference Ground-Water Flow
Model: U.S. Geological Survey, Open-File Report 96-485.
Harbaugh, A. W., Banta, E. R., Hill, M. C., and McDonald, M. G., 2000, MODFLOW-2000, theU.S. Geological Survey modular ground-water model -- User guide to modularization
concepts and the Ground-Water Flow Process: U.S. Geological Survey Open-File
Report 00-92, 121 p.
Hutchison, W.R., 2017a, GMA 13 Technical Memorandum 16-08 Final, Sparta, Queen City,
and Carrizo-Wilcox Aquifers: Summary of Scenario 9 Drawdown and Outcrop
Results, 13 p.
Hutchison, W.R., 2017b, GMA 13 Technical Memorandum 16-04 Final, Yegua-Jackson
Aquifer: GAM Predictive Simulations, 7 p.
Hutchison, W.R., 2017c, Desired Future Condition Explanatory Report (Final) CarrizoWilcox/Queen City/Sparta Aquifers for Groundwater Management Area 13, 481 p.,
http://www.twdb.texas.gov/groundwater/dfc/docs/GMA13_DFCExpRep_CWQCSp.
pdf
Hutchison, W.R., 2017d, GMA 13 Explanatory Report – Final Yegua-Jackson Aquifer, 152 p.,
http://www.twdb.texas.gov/groundwater/dfc/docs/GMA13_DFCExpRep_YJ.pdf
Hutchison, W.R., 2017e, GMA 13 Technical Memorandum 17-01 Final, Extension of GAM
Calibration Period for Carrizo-Wilcox, Queen City, and Sparta Aquifers, 81p.

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 27 of 36

Kelley, V.A., Deeds, N.E., Fryar, D.G., and Nicot, J.P., 2004, Groundwater availability models
for the Queen City and Sparta aquifers: Contract report to the Texas Water
Development Board, 867 p.
National Research Council, 2007, Models in Environmental Regulatory Decision Making
Committee on Models in the Regulatory Decision Process, National Academies Press,
Washington D.C., 287 p., http://www.nap.edu/catalog.php?record_id=11972.
Oliver, W., 2010, GAM Task 10-012 Model Run Report: Texas Water Development Board,
GAM Task 10-012 Report, 48 p.,
http://www.twdb.texas.gov/groundwater/docs/GAMruns/Task10-012.pdf
Texas Water Code, 2011, http://www.statutes.legis.state.tx.us/docs/WA/pdf/WA.36.pdf.

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 28 of 36

Appendix A
Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, and Sparta
Aquifers Summarized by County, River Basin, Regional Water Planning Area,
and Groundwater Conservation District in Groundwater Management Area 13

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 29 of 36
TABLE A.1 MODELED AVAILABLE GROUNDWATER FOR THE CARRIZO-WILCOX, QUEEN CITY, AND
SPARTA AQUIFERS SUMMARIZED BY COUNTY IN GROUNDWATER MANAGEMENTAREA 13. RESULTS ARE IN ACRE-FEET PER YEAR.

CountyAtascosa
Bexar
CaldwellDimmitFrio
GonzalesGuadalupe
Karnes
La Salle
Maverick
McMullenMedinaUvaldeWebb
WilsonZavala
GMA 13 Total

2020

2030

2040

2050

2060

2070

72,95981,47461,551
4,129
119,724
90,27352,528
1,042
7,848
2,042
7,279
2,657
2,975
916
111,70735,653654,757

76,01780,81761,5514,129
90,50990,27347,844
1,085
7,848
2,042
7,279
2,648
1,231
916
106,677
35,305616,172

76,73980,348
58,1084,129
88,274
94,05145,776
1,146
7,848
2,001
4,629
2,647
828
916
107,759
35,171
610,369

78,31579,47058,1084,129
86,185
94,41547,995
1,212
7,848
1,914
4,629
2,647
828
916
109,041
35,071
612,723

79,74978,97754,4954,129
84,104
94,66747,965
1,264
7,848
1,570
4,629
2,646
828
916
110,593
34,750609,130

81,18978,80754,495
4,129
82,08994,67547,833
1,296
7,848
1,531
4,629
2,646
828
916
112,193
34,695609,802

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 30 of 36
TABLE A.2 MODELED AVAILABLE GROUNDWATER FOR THE CARRIZO-WILCOX, QUEEN CITY, AND
SPARTA AQUIFERS SUMMARIZED BY RIVER BASIN IN GROUNDWATER MANAGEMENTAREA 13. RESULTS ARE IN ACRE-FEET PER YEAR.

River Basin

2020

2030

2040

2050

2060

2070

Colorado
Guadalupe
LavacaNuecesRio Grande
San Antonio
GMA 13 Total

593
207,880273
310,1222,196
133,693654,757593
203,631273
281,200
2,196
128,278
616,172593
201,729273
276,645
2,155
128,974
610,369593
204,002273
276,208
2,068
129,578
612,723593
201,193273
275,1212,028
129,922609,130593
201,286273
274,730
1,990
130,929
609,802

TABLE A.3 MODELED AVAILABLE GROUNDWATER FOR THE CARRIZO-WILCOX, QUEEN CITY, AND
SPARTA AQUIFERS SUMMARIZED BY REGIONAL WATER PLANNING AREA INGROUNDWATER MANAGEMENT AREA 13. RESULTS ARE IN ACRE-FEET PER YEAR.

Regional Water Planning
Area
L
M
N
GMA 13 Total

2020

2030

2040

2050

2060

2070

644,5202,958
7,279
654,757

605,934
2,958
7,279
616,172

602,823
2,917
4,629
610,369

605,2642,829
4,629
612,723

602,016
2,485
4,629
609,130

602,726
2,447
4,629
609,802

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 31 of 36
TABLE A.4 MODELED AVAILABLE GROUNDWATER FOR THE CARRIZO-WILCOX, QUEEN CITY, AND
SPARTA AQUIFERS SUMMARIZED BY GROUNDWATER CONSERVATION DISTRICT IN
GROUNDWATER MANAGEMENT AREA 13. RESULTS ARE IN ACRE-FEET PER YEAR.

Groundwater
Conservation District
Evergreen UWCD
Gonzales County UWCD
Guadalupe County GCD
McMullen GCD
Medina County GCD
Plum Creek CD
Uvalde County UWCD
Wintergarden GCD
No District-Bexar County
No District-Caldwell County
No District-Gonzales County
No District-Maverick County
No District-Webb County
GMA 13 Total

2020

2030

2040

2050

2060

2070

305,432
130,21252,528
7,279
2,657
20,633
2,975
47,63081,474
921
59
2,042
916
654,757

274,288130,21247,844
7,279
2,648
20,633
1,231
47,28280,817
921
59
2,042
916
616,172

273,917130,954
45,776
4,629
2,647
20,224828
47,14980,348
921
59
2,001
916
610,369

274,754
131,318
47,995
4,629
2,647
20,224828
47,04879,470
921
59
1,914
916
612,723

275,710
128,535
47,965
4,629
2,646
19,647828
46,72778,977
921
59
1,570
916
609,130

276,768
128,543
47,833
4,629
2,646
19,647828
46,67378,807
921
59
1,531
916
609,802

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, andYegua-Jackson aquifers in Groundwater Management Area 13
October 27, 2017
Page 32 of 36

Appendix B
Total Pumping Associated with Modeled Available Groundwater Run for the
Carrizo-Wilcox, Queen City, and Sparta Aquifers Split by Model Layers for
Groundwater Conservation Districts in Groundwater Management Area 13

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers in Groundwater
Management Area 13
October 27, 2017
Page 33 of 36
TABLE B.1

TOTAL PUMPING BY MODEL LAYER ASSOCIATED WITH THE MODELED AVAILABLE GROUNDWATER RUN FOR THE CARRIZOWILCOX, QUEEN CITY, AND SPARTA AQUIFERS IN GROUNDWATER MANAGEMENT AREA 13 SUMMARIZED BY GROUNDWATERCONSERVATION DISTRICT (GCD).

Groundwater
Conservation
District
Evergreen UWCD
Evergreen UWCD
Evergreen UWCD
Evergreen UWCD
Evergreen UWCD
Evergreen UWCD
Evergreen UWCD
Total
Gonzales County
UWCD
Gonzales County
UWCD
Gonzales County
UWCD
Gonzales County
UWCD
Gonzales County
UWCD
Gonzales County
UWCD
Gonzales County
UWCD Total

Model Layer(Aquifer)

2012

2020

2030

2040

2050

2060

2070

2,726
13,614
199,165

2,723
13,614
199,165

2,166
10,797
171,394

2,056
10,455
171,475

1,955
10,133
172,735

1,870
9,723
174,186

1,792
9,359
175,686

374

374

374

374

374

374

374

370

370

370

370

370

370

370

89,18689,18689,18689,18689,18689,18689,186

305,436

305,432

274,288273,917274,754

275,710

276,768

1 (Sparta)

3,554

3,554

3,554

3,554

3,554

3,554

3,554

3 (Queen City)

5,351

5,351

5,351

5,351

5,351

5,351

5,351

5 (Carrizo)

83,284

83,284

83,28484,026

84,39081,607

81,6156 (UpperWilcox)

0

0

0

0

0

0

0

7 (Middle
Wilcox)

12,187

12,187

12,187

12,187

12,187

12,187

12,1878 (Lower
Wilcox)25,83625,83625,83625,83625,83625,83625,836130,212130,212130,212130,954

131,318

128,535

128,543

1 (Sparta)
3 (Queen City)
5 (Carrizo)
6 (UpperWilcox)7 (Middle
Wilcox)
8 (Lower
Wilcox)GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers in Groundwater
Management Area 13
October 27, 2017
Page 34 of 36

Groundwater
Conservation
DistrictGuadalupe County
GCD
Guadalupe County
GCD
Guadalupe County
GCD
Guadalupe County
GCD
Guadalupe County
GCD Total
McMullen GCD
McMullen GCD
McMullen GCD
McMullen GCD
McMullen GCD
McMullen GCD
McMullen GCD
Total
Medina County
GCD
Medina County
GCD
Medina County
GCD

Model Layer(Aquifer)

2012

2020

2030

2040

2050

2060

2070

25,14325,143

20,771

16,367

16,47016,783

16,862

0

0

0

0

0

0

0

3,299

6,290

5,978

7,377

8,700

8,435

8,224

19,59021,09421,09422,031

22,82522,74722,74748,032
89
134
7,002

52,528
89
134
7,056

47,844
89
134
7,056

45,776
89
134
4,405

47,995
89
134
4,405

47,965
89
134
4,405

47,833
89
134
4,405

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

7,226

7,279

7,279

4,629

4,629

4,629

4,629

5 (Carrizo)

545

545

537

536

535

535

534

6 (UpperWilcox)

0

0

0

0

0

0

0

7 (Middle
Wilcox)

1,248

1,248

1,248

1,248

1,248

1,248

1,248

5 (Carrizo)
6 (UpperWilcox)7 (Middle
Wilcox)
8 (Lower
Wilcox)1 (Sparta)
3 (Queen City)
5 (Carrizo)
6 (UpperWilcox)7 (Middle
Wilcox)
8 (Lower
Wilcox)GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers in Groundwater
Management Area 13
October 27, 2017
Page 35 of 36

Groundwater
Conservation
DistrictMedina County
GCD
Medina County
GCD Total
Plum Creek CD
Plum Creek CD
Plum Creek CD
Plum Creek CD
Plum Creek CD
Plum Creek CD
Total
Uvalde County
UWCD
Uvalde County
UWCD
Uvalde County
UWCD
Uvalde County
UWCD
Uvalde County
UWCD Total
Wintergarden GCD
Wintergarden GCD
Wintergarden GCD
Wintergarden GCD

Model Layer(Aquifer)
8 (Lower
Wilcox)3 (Queen City)
5 (Carrizo)
6 (UpperWilcox)7 (Middle
Wilcox)
8 (Lower
Wilcox)5 (Carrizo)
6 (UpperWilcox)7 (Middle
Wilcox)
8 (Lower
Wilcox)1 (Sparta)
3 (Queen City)
5 (Carrizo)
6 (UpperWilcox)

2012

2020

2030

2040

2050

2060

864

864

864

2,657
22
6,057

2,657
22
6,057

0

2070

864

864

864

864

2,648
22
6,057

2,647
22
6,057

2,647
22
6,057

2,646
22
6,057

2,646
22
6,057

0

0

0

0

0

0

5,301

4,838

4,838

4,838

4,838

4,261

4,261

9,714

9,714

9,714

9,306

9,306

9,306

9,306

21,095

20,633

20,633

20,224

20,224

19,647

19,647

828

828

828

828

828

828

828

3,622

2,147

402

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

4,451
983
2
32,9622,975
983
232,962

1,231983
232,615828983
232,481828
983
232,381828
983
2
32,060828
983
232,005

9,261

9,261

9,261

9,261

9,261

9,261

9,261

GAM Run 17-027 MAG: Modeled Available Groundwater for the Carrizo-Wilcox, Queen City, Sparta, and Yegua-Jackson aquifers in Groundwater
Management Area 13
October 27, 2017
Page 36 of 36

Groundwater
Conservation
District
Wintergarden GCD
Wintergarden GCD
Wintergarden
GCD Total

Model Layer(Aquifer)
7 (Middle
Wilcox)
8 (Lower
Wilcox)

2012

2020

2030

4,006

4,006

4,006

416

416

47,63047,630

2040

2050

2060

2070

4,006

4,006

4,006

4,006

416

416

416

416

416

47,282

47,14947,04846,727

46,673