When the well is dry we all know the wealth of water.

-Ben Franklin The Edwards Aquifer: A Texas Treasure

xtending 176 miles from Brackettville in Kinney County to Kyle in Hays County, the Edwards Aquifer is one of the nation's most productive groundwater resources. In many respects, the Edwards Aquifer has shaped this area of south central Texas. The lives and livelihoods of more than 1.3 million people living in the region depend on the high quality, replenishable water found in the Edwards Aquifer. Cities, towns, rural communities, farms and ranchlands alike rely on the aquifer's water for municipal, domestic, agricultural, industrial, and recreational purposes.

The Edwards Aquifer is a complex network of drainage, recharge and For centuries, artesian/ reservoir areas, underlying 8,000 square miles and thirteen people have counties. The Edwards Aquifer, one of the largest aquifers in the south­ settled in the western United States, is the primary source of water for the people it Edwards Aquifer serves. In 1977, the Edwards Aquifer was designated the first Sole Source region because Aquifer by the Environmental Protection Agency. San Antonio, the third of the largest metropolitan area in the state and the tenth largest in the nation, abundance of currently is the most populated city in the U. S. that obtains its entire water springwater. supply from a single aquifer. The Edwards Aquifer also supports a unique system of plant and animal life, some of which exist nowhere else in the world.

The need for planning and protection is continuous. If the long term average annual pumpage exceeds the long term average annual recharge, water levels in the aquifer will drop and springflow will cease. To the people of this region, the protection and proper management of the Edwards Aquifer means economic stability, environmental integrity, preservation of a unique system of plant and animal life, and a continued high quality of life.

2 The Edwards Underground Water District: A Mission of Stewardship

Q roundwater is one of Texas' most valuable resources. About 70 percent of the water currently used in the state is groundwater. In south central Texas, groundwater is particularly important to the 1.3 million people who rely upon the Edwards Aquifer as their primary source of water.

Following the drought of the l 950's, concerned citizens worked with state and local leaders to provide for local protection of the Edwards Aquifer through the creation of an under­ ground water district. The Edwards Underground Water District, created by the State Legislature in 1959, is the manifestation of the region's commitment to protect and preserve this unique and precious resource.

Since its creation, the Edwards Underground Water District has initiated much of the groundwater resource planning for the Edwards Aquifer region.

The District's boundaries currently lie within the counties of Bexar, Comal, and Hays and its affairs are governed The District's by a 12-member board, elected by popular vote. The Edwards Aquifer, mission of stewardship however, cannot be divided according to political boundaries. For this reason, extends throughout the Edwards Underground Water District is committed to continuing its the Edwards Aquifer programs throughout the aquifer region so that residents can continue to region so that residents receive the benefits of an indispensable resource. can continue to enjoy the benefits At the present time, the quality of water in the Edwards Aquifer surpasses of an recognized water quality standards. To ensure both the quality and the indispensable resource. quantity of water in the aquifer, holistic and coordinated management is critical.

3 The Edwards Aquifer Provides A Valuable Resource to South Central Texas

Photo courtesy of Sa 11 A11to11io Convention and Visitor's Bureau

grasslands of south central Texas, the To Early Settlers Downstream Users Also Rely waters and underground caverns of Springs Were Like Paradise on the Edwards Aquifer the aquifer provide a natural habitat for a number of endangered plant and animal species. There are three known The history of thi s area is rich with People living in the Edwards Aquifer endangered animal species living in accounts of people and their depen­ region are not the only ones who rely the springs, either in or near the dence upon the springs and rivers on its waters. In San Marcos and New mouths of Comal and San Marcos of this area. Archaeological digs at Braunfels, the springs support a springs: the Texas Blind Salamander, San Marcos Springs reveal that man thriving recreation and tourism the Fountain Darter, and the San lived there as early as 13,000 years economy. The water then flows Marcos Gambusia. The San Marcos ago. downstream where thousands of Salamander, listed as threatened, is people depend on it for domestic use, restricted to the headwaters of the San The "Camino Real," or King's irrigation, industry and recreation. Marcos and Comal Rivers. Texas Highway, which was completed in Wildrice, also endangered, is an 1697 by the Spanish, passed by the Under normal conditions, the Comal aquatic grass that is indigenous to the San Marcos, Comal, and San Antonio and San Marcos Springs supply San Marcos River. Species such as Springs. In San Antonio, the first approximately 30 percent of the base the Widemouth Blindcat, the Tooth­ acequia, or water ditch, was finished flow of the Guadalupe River. In times less Blindcat, and blind shrimp can be in 1730 and provided an elaborate of drought, the springs provide up to found deep beneath the earth's system of Springwater di spersal for 70 percent of the base flow. Farmers surface, living in the pore spaces of cooking, drinking, and irrigation. In along the Guadalupe River rely on the Edwards Limestone. 1845, German settlers led by Prince this flow to irrigate their orchards and Carl Sol ms of Braunfels arrived and row crops, to water their livestock, established the settlement known as and for domestic needs. New Braunfels along the Comal Continued Economic Vitality River. Depends on Clean, Fresh Water Through the late 1800's, springs provided the primary source of water Aquifer Sustains A Unique Water from the Edwards Aquifer has for people living in the area. The first System of Plant and Animal Life supported civilization in south central well was drilled into the Edwards Texas for thousands of years, and it Aquifer in 1865. By 1900, wells continues to be the primary source of had become the major suppliers of Just as the aquifer is our sole source water for the area. water. of water, it is also the life-source for Because of the renewable nature of an abundance of wildlife that live in Maintaining the clean and plentiful this precious resource, the Edwards the aquifer region. supply of water that is stored by Aquifer continues to be the basic nature in the Edwards Aquifer is, and building block of life for everyone In addition to the familiar species of always will be, essential to the growth who lives and works in the region. wildlife which flourish in the hills and and prosperity of the Edwards region. 4 The Edwards Aquifer and its Drainage Area Includes All or Parts of 13 Counties

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NoS1gmficant 102.600 Acre Feet 149.JOO Acre Feet IS4.400 Am: Feet 6S.200Acrc Fut 105.200Acre Feet Rechugc J6.300AcreFcct Frio·Sabinal Seco-Hondo-Mcdina Helotcs·Salildo Cibolo-Ory Comal Guadalu pe Blanco Average Annual Recharge from the Region's River Basins

5 From a regional perspec­ tive, the movement of Complex Aquifer water through the Edwards Aquifer appears to be simple. System Has Three

The primary geologic component of the Major Components Edwards Aquifer is Edwards Limestone, The Edwards Aquifer is a network of drainage, which occurs in three recharge and artesian/ reservoir areas, which major and distinct seg­ underlie 8,000 square miles and ments: the Edwards Plateau, the Balcones thirteen south central Texas counties. Fault Zone, and the Gulf Coastal Plain. Drainage Area There are also three hydrologic components in the Edwards Aquifer The Edwards Plateau system: a Drainage Area, The first and largest component of the a Recharge Area, and an aquifer system, with an area of about Artesian/ Reservoir Area. 4,400 square miles, is the Drainage Area, also known as the Edwards Precipitation falling on Plateau. the drainage area is transported by streams to Land surface on the Edwards Plateau the Balcones Fault Zone, ranges in altitude from 2,300 feet where it penetrates the above mean sea level in the west to about 1,000 feet above mean sea level ground and recharges the in the east. Vegetation on the plateau aquifer. The groundwater is primarily woodlands comprised of then moves by gravity various species of oak, mesquite, and through the pore spaces juniper. Large areas of woodlands on in the limestone from the plateau have been cleared to areas where the water provide increased rangeland for levels are at higher eleva­ grazing livestock. Drainage Area continue to flow for tions to areas where the long periods after storms cease water levels are at lower because the water stored in porous elevations (toward the The Drainage basins on the Edwards limestone slowly migrates out of the major springs). Water is Plateau funnel stormwater runoff into rock and sustains the base flow of the streams. withdrawn by wells or streams that flow across the recharge area. Since most recharge to the discharged at the springs. aquifer occurs through streambeds, the funneling effect is an important From this generalized function of the Drainage Area. explanation, the aquifer Recharge Area functions in a seemingly uncomplicated manner. The Edwards Plateau is composed of The Balcones Fault Zone A more detailed examina­ Edwards and Glen Rose Limestones tion of the Edwards and receives recharge directly from The second component of the aquifer Aquifer, however, rainfall and runoff. Edwards Lime­ system is the Edwards Limestone's indicates that the flow stone is porous and some of the water exposure along the Balcones Fault is very complex. is stored after the rainfall stops. Zone, also known as the Recharge Streams that originate from the Area. This portion of the aquifer has 6 , Ab out !Sllli of precipitation falling on the 0 ue.1 i~ lost buk to the .atmosphere by ev.apo~.atL~ n due to wum tempcruurcs or by tr.ansp1r.at1on of water v.apor horn vegeution.

Drainage Area Recharge Area Artesian/Rese rvoir Area

Edwards Plateau Rechuge d.1ms slow storm runoff R.liin over 1his are.1 below the over the Rechuge Zone so more of Rechuge Zone hu little effect Water Tuble Aquifer it runs into the Aquifer. on rechuge . Su rfaceW.1ter Reservoi r · ~

* .. J - ,: ~ Su1(•ct suums flow .:5< beyond 1htAqullt1i1U illthwaytotbebays ind tstuulnofthtGulf Co•sl

.,.._._... Reluively Impermeable Younger Formations

Edwuds & Associ.ated B.alconesF.1ultZone Limes1ones

Flowing .lfle1'i.1n wells .ind springs eir:ist where hydr.iulic pressure is sufficient 10 force the w.iter up through wells .ind faulu to the surface. Rel.itivelyimpermeable Water in the Artesi.11n/Reservoir Are.11 of Older Form.itions the porous Edwnds limestone1 is confined under pressure between two rel.itively impermeable geologic formations.

an area of about 1,500 square miles. Artesian/ Reservoir Area of this interface is highly mineralized and not potable. On the fresh water Many closely spaced, nearly vertical side of this line, flow is deflected faults occur along the relatively The Gulf Coastal Plain northeastward toward the major narrow Balcones Fault Zone, springs in New Braunfels and San exposing the fractured Edwards The final component of the aquifer Marcos. Limestone at land surface. Recharge system lies deep beneath the Gulf features such as caverns and sinkholes Coastal Plain. The Del Rio Clay and The direction and rate of movement are common in this area. Live Oak other overlying, confining formations of water in the aquifer are affected by and juniper trees are also a part of the make this part of the Edwards the extremely complicated physical native landscape. Limestone the Artesian/ Reservoir characteristics of the Edwards Area. The Gulf Coastal Plain is a Limestone such as faulting and As the streams cross the fault zone, gently rolling landscape and altitudes transmissivity, or the capability of much of the flow percolates through vary from about 1,200 feet in the water to move through the aquifer. the streambeds into the aquifer. western part of the area to about 600 During low-flow periods, virtually all feet in the eastern part. This portion of The part of the aquifer with the streamflow is recharged to the the aquifer system has a surface area greatest pore space and the highest aquifer. Except during floods, the of about 2,100 square miles. yielding wells is a relatively narrow streams flowing from the western band from near San Antonio part of the plateau lose most of their The Artesian/ Reservoir Area, with its northeastward through the vicinity of water through recharge to the many pore spaces and complex the two largest springs. Wells in this Edwards Aquifer and generally are network of solution openings, has a band commonly yield water at rates of dry when they reach the Gulf Coastal great capacity for storing and moving 6,000 to 7 ,000 gallons per minute. Plain. During higher flow periods, water. In this area, the groundwater Wells in the northern and western streamflow commonly exceeds the moves east-northeast. The southern parts of the aquifer produce much less recharge rate and much of the water and eastern boundary of the Edwards water, with wells that produce only flows across the recharge area to the Aquifer is known as the Fresh/Saline several gallons per minute being Coastal Plain. Water Interface. Water south and east common in northern Bexar County. 7 1988 Intersection of Interstate Highway 410 and San Pedro Avenue, San Antonio, Texas illustrates population growth in Bexar County

8 Increasing Demands Threaten Water Supply

Photn courtesy of San A11ro11in Com·enrion and Visitor's Bureau

Growing Population more, during the past 50 years, many Average annual recharge to the Causes Changes in areas within the region have changed Edwards Aquifer equals 640,000 acre-feet, with an historical range Water Use from a predominantly rural to a more urban environment. from 43,000 to over 2 million acre feet. Increasing demands on the The first settlements in the area were In response to population increases, Edwards Aquifer, coupled with wide located near natural spring outlets. industrial growth, agricultural ranging recharge amounts has resulted Until the first well was drilled into the expansion, and demographic changes, in large fluctuations in water levels. Edwards Aquifer in 1865, water from water withdrawals through wells from This, at times, has resulted in depleted the aquifer was obtained only from the Edwards Aquifer have also wells and dry springs. With a regional springs. In the 18th and 19th increased. Since 1940, total annual population predicted to surpass 2.3 centuries, only a small part of the pumpage in the region has increased million by the year 2020, increased springflow was needed to sustain the by more than 300 percent, from reliance on the Edwards Aquifer will area's sparse population. 120, 100 acre feet to 489 ,000 acre feet cause wells and springs to dry up in 1990. (An acre foot equals the more frequently and for longer Wells became the major suppliers of amount of water needed to cover one periods. A limited resource necessi­ water after 1900 when the area acre of surface area to a depth of one tates limiting demands upon it. population reached 100,000. Since foot, or 325,851 gallons.) 1940, the population in the Edwards Aquifer region has increased at a rate Per Capita Use of about 20,000 people per year. Slowing

Bexar County, where San Antonio is located, represents most of the area's Through the late l 980's, per capita population. This city has increased in water use in the urban areas of the population from about 200,000 in Historically, the availability of region continued to increase, reflect­ 1940 to over 1, 100,000 in 1990. water from the Edwards Aquifer has ing the changing lifestyles and Rapid development of light industry been sufficient to meet the demands industrial expansion that had and service companies have accompa­ in the area. Continued urban and occurred. However, current events nied the population increases. industrial development, however, will over the last few years have prompted result in increased demands on the a gradual reversal of that trend. Since The trend toward growth is consistent aquifer. 1980, attention has increasingly throughout the Edwards Aquifer focused on the water resources of this region. Between 1940 and 1990, the Water resource planners project that region. Federal lawsuits, state actions, population of Uvalde increased from by the year 2020, demand for water in local ordinances and intensive water 6,679 to 14,729; the population of the Edwards Aquifer region could conservation education efforts have Hondo increased from about 3,500 to exceed 850,000 acre feet per year and created an increased public awareness 6,012; and San Marcos has increased that "mining" of the aquifer could of the need to conserve the region's from about 6,000 to 28,743. Further- begin as soon as the year 2000. principal source of water. 9

The Edwards Underground Water District is a regional unit of government created in 1959 by the Texas Legislature for the purpose of conserv­ ing, protecting, and recharging the groundwater in the Edwards Aquifer.

To accomplish this purpose, the District is em­ powered through its enabling legislation.

As citizens in the region become more aware of their water supply and the critical importance of planning for future water needs, it is more important than ever to understand the limitations and capabilities of this complex resource.

Under the leadership of the Board of Directors, the Edwards Underground Water District will continue its mission of stewardship of the Edwards Aquifer. . . to conserve . .. to preserve and protect. . .to prevent waste and pollution . . . to develop comprehensive plans ... to publish plans and information ... to increase recharge ... for present and future generations.

11 "... TO PREVENT WASTE AND

POLLUTION. .. II

• responding to leaks and other distribution systems. Nationwide, Water Quality sources of contamination unseen leaks account for an estimated • working to upgrade the existing 40 percent water loss rate. In the Edwards Rules Edwards region, however, Di strict •conducting groundwater contami­ leak detection specialists are helping According to the U. S. Environmental nation investigations area municipalities locate these Protection Agency, water in the • conducting hydrocarbon storage hidden water wasters. Edwards Aquifer surpasses all federal facility compliance inspections drinking water standards. Many of the • development of an Emergency Outdated plumbing fixtures are also District's programs focus on maintain­ Spill Response Plan substantial wasters of water. Design ing these high water quality standards • protecting sensitive areas such as improvements in toilets, showerheads, for the people who rely on the sinkholes and caves from contamina­ and faucet fixtures allow appliances Edwards Aquifer as their principal tion and maintaining them as natural to use less than half of the water used source of water. recharge points by their older counterparts. The • closing abandoned wells. District has been active in encourag­ Due to the faulting and fracturing ing the adoption of municipal associated with Edwards Limestone, ordinances requiring the use of ultra­ the Edwards Aquifer is extremely low-flow (ULF) plumbing fixtures in vulnerable to surface and subsurface Water Conservation new construction. Since this effort pollution. In September of 1986, the began, seven cities within the District's Board of Directors adopted Edwards Aquifer region have adopted a non-degradation policy concerning Water conservation represents an ULF ordinances. the Edwards Aquifer. additional source of water. Resource planners estimate that common-sense In response to that mandate, and in conservation efforts can result in at Information and least a 10-15 % reduction in water use. accordance with its enabling statute, Education the District carries out a number of programs aimed at identifying and Water quantity is affected both by the abating potential threats to both the amount of water that is added to the One of the most important factors quality and quantity of water in the aquifer and the amount of water that affecting how people use water from Edwards Aquifer. These programs is withdrawn. The District carries out the Edwards Aquifer is how well they include: a number of innovative programs to understand the nature and characteris­ eliminate waste and develop addi­ tics of the resource itself. The Di strict • monitoring development on the tional sources of water. believes that a well informed citizenry Recharge Zone will be more responsive and better • monitoring and inspecting One major source of wasted water equipped to meet the challenges hazardous material storage facilities comes from leaks in underground fac ing them with respect to resource 12 "... TO CAUSE INVESTIGATIONS TO BE MADE TO DETERMINE THE MOVEMENT OF UNDERGROUND WATER AND THE

QUANTITY THEREOF .. II

management. Because of this belief, has collected a large body of physical the District conducts a comprehensive Data Collection and data. Due to the sheer volume of data public information and education pro­ Management and the aquifer's sizable geographic gram targeting children, adults, and a area, computer processing is required. variety of other groups and organiza­ In 1989, the District began develop­ tions. Fostering a water conservation Despite years of study, scientists still ing a geographic information system ethic among present and future water are not certain how much water is in (GIS) capable of storing, analyzing, users is the cornerstone of the the Edwards Aquifer. Although the and managing the wide variety of District's overall conservation effort. U. S. Geological Survey estimates information required to monitor the between 25 and 50 million acre feet, impact of human activities on the The District's education program is a it is difficult to measure precisely how quantity and quality of water in the multi-level, multi-faceted, in-school much water is in the aquifer because Edwards Aquifer. Data sets have been effort which targets the special needs of the limestone's porosity and the compiled on significant recharge of teachers and students alike. The interconnected configurations of open features, geology, drainage areas education program includes teacher caverns and microscopic pores. The over the recharge zone in Bexar workshops, in-service education, high Edwards Underground Water District County, and other information which quality audio-visual materials, multi­ conducts several programs aimed at supports District objectives and level curricula and resource materials, providing answers to some of the programs. and theatrical presentations. unknown factors. At any given time, the District has Information programs include a Geologists understand that continuous underway a variety of long- and speakers' bureau, field trips, free monitoring of the water supply is key short-term investigations into the standing displays for use in libraries, to its protection. The District main­ nature and characteristics of the banks, malls and other public spaces, tains one of the most comprehensive Edwards Aquifer. Examples of such a seasonally-intensive conservation data collection programs in Texas for studies include: an investigation into effort, water conservation materials, an underground water supply. A the storage trends in the Edwards and a variety of community outreach network of over I 00 monitoring wells, Glen Rose Aquifers; the potential for programs, and a quarterly newsletter located throughout the Edwards saline water intrusion into the fresh distributed to citizens upon request. Aquifer region, enables District water zone of the Edwards Aquifer; For more information on these. geologists to maintain constant watch and the potential for increasing programs call the District's Public over water quality and quantity. recharge to the Edwards Aquifer. Information Office at 222-2204 or 1-(800)-292-1047. In its effort to uncover the mysteries of the Edwards Aquifer, the District 13 Regional Water "... TO DEVELOP Supply Planning COMPREHENSIVE PLANS ... II

Achieving regional solutions to water problems through consensus is a primary goal of the Edwards Underground Water District.

As early as 1983, the District joined with the City of San Antonio and The Future of the other interested parties from across the region to develop the 1988 Edwards Aquifer Regional Water Plan. This Plan contained four major components and continues to represent the region's of the area and how these needs are to best attempt at forging a consensus­ Elected state and local officials, be met. Information needs include based water management plan. The professional water managers, and data for determining the maximum components of the Regional Water interested citizens from across the recharge potential and the maximum Plan were: the construction of surface Edwards Aquifer region have that can safely be withdrawn from the water reservoirs, the development of different but important concerns aquifer during periods of various water reuse programs, conservation, relative to alternatives for future climatic conditions. All of this must and allocation. Although the enabling water management. Because of the be accomplished without endangering legislation for the Regional Water interconnectedness of the aquifer the quality of the resource and Plan failed in the 1989 legislative system, and competing interests for without causing severe hardship for session, the guiding principles behind limited supplies, each diverse group the various water users. that Plan still represent the best must be consulted and their input approach for effective management of carefully considered before manage­ Long and continuous study efforts, the Edwards Aquifer. ment decisions are finalized. with well defined objectives and well organized study approaches must be The failure of the legislative effort left Alston and Freeman ( 197 5) describe pursued. The Edwards Underground the people of this region with no plan decision makers as sociopolitical Water District is committed to long­ in place to protect their future water people "who must bargain with and short-term groundwater investiga­ interests. Nor is there an effective diverse clients, knowing that the tions aimed at addressing these issues. regionwide mechanism for resolving public good is defined in many the critical and complex issues which conflicting ways by intensely com­ Considerable work has been under­ face them. petitive and self-interested groups. taken by various groups and entities Such decision makers know that goals in the Edwards Aquifer region to The nature and characteristics of this are fluid, multiple, and inconsistent, address present and future water very special resource require careful multidimensional and incommensu­ needs. But much work remains to be planning and equitable management. rable. They also know that no fixed done. The need for planning is The issues are not purely technical, solutions are possible, regardless of ongoing. The need for management is but are political and economical as their technical or economic elegance." critical. The need for stewardship is well. The key to building a sound essential. To protect both the quality consensus is through preparation and In an expanding economy with and quantity of water, the resource participation-posing the right increasing population, water use will must be managed as a whole. The questions, collecting and analyzing . increase and the Edwards Aquifer will responsibilty rests with all those who data, interpreting the information, continue to provide the primary rely upon the Edwards Aquifer. delineating the alternatives, deciding source of water for the region. State on a course of action and doing these and local water managers as well as activities through a collaborative decision makers need the best process that is open, equitable, and information available to make Photo opposite page fair. decisions concerning the water needs Recharge to Seco Sinkhole (December 199 I)

14

Plioro courtesy of San A111011io U g/11/ Tommy H11lr,r.: re11

16 0 Printed on Recycled Paper EDWARDS UNDERGROUND WATER DISTRICT 1615 N. St. Mary's• San Antonio, Texas 78215 512-222-2204. 1-800-292-1047