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Of Texas’ 196 lakes – Caddo Lake – is the only natural lake.*

Ensuring a plentiful, clean water supply for Texas’ growing population continues to be a challenge. Texas has enormous climactic variety; average annual rainfall varies widely.

Texas has many rivers, but most have their origins in the drier areas of the state and generally cannot support large populations until reaching the central and southeastern part of the state. Texas’ gentle topography means it also has few natural bodies of surface water. Of the state’s 196 lakes, only Caddo Lake in East Texas is not man-made.

Texas also has many underground water formations known as aquifers, upon which agriculture, many cities and industries depend. Aquifers can be ancient bodies of water with very little recharge from rainfall, such as the Ogallala Aquifer in the Panhandle, or bodies that are continually recharged, such as the Edwards Aquifer in Central Texas. Not all aquifers contain fresh water. Most contain at least some saline water; the water in many contains minerals, salts or naturally occurring radiation in excess of drinking water standards.18 Uses for these waters are limited without treatment.

Exhibit 9

Average Annual Texas Precipitation,

Texas map showing different zones of rainfall

(Texas map showing different zones of rainfall, Text Alternative)

Agricultural producers, urban, suburban and rural communities, industries and recreational interests all require water. Careful long-term planning and conservation is necessary to provide a limited supply of water to an increasing population. In 2004 (the most recent data available), Texas consumed 15.5 million acre-feet of both ground and surface water.19 The Texas Water Development Board (TWDB) has projected that this demand could rise to 21.6 million acre-feet by 2060.20 An acre-foot is the amount of water needed to cover an acre of land to a depth of one foot, or 325,851 gallons, about the average annual use of two families.

Texas has three state agencies with jurisdiction over water issues. TWDB is responsible for planning and funding projects that enhance water availability. The Texas Commission on Environmental Quality (TCEQ) is responsible for protecting the state’s water quality and allocating the use of surface water; groundwater is neither allocated nor managed by a state agency, with a few exceptions (see the Availability section). And the Texas Parks and Wildlife Department (TPWD) ensures that the state’s wildlife, including the vital fish, shrimp and oyster industries, have sustainable supplies of fresh water.

Texas Hydrology

Texas’ average annual rainfall varies from 10 inches in the west to 55 inches in the east (Exhibit 9).21

High average temperatures, which range from less than 70 degrees Fahrenheit in the Panhandle to more than 82 degrees Fahrenheit in the Lower Rio Grande Valley, cause water evaporation to exceed precipitation in most of the state. The result is a semi-arid climate (less than 20 inches of precipitation annually) in the western half of Texas, except in arid far West Texas, with 10 inches or less of precipitation annually.

Exhibit 10

Major River Basins of Texas

Texas map showing 23 river basins

(Texas map showing 23 river basins, Text Alternative)

Surface Water

Texas’ 191,000 miles of rivers and streams provide about 40 percent of the total water used in the state or 15.5 million acre-feet in 2004.22 Texas has 23 surface water basins; 15 are major river basins and eight are coastal river basins that lie between two river estuaries on the Gulf (Exhibit 10).

Texas has one advantage over other states in that 11 of its 15 major rivers begin and end within the state’s boundaries, greatly simplifying river management. The Canadian River in the Panhandle, the Red River in the North, the Pecos River in West Texas and the Sabine River in the East are shared with neighboring states and governed by interstate agreements and commissions. The Rio Grande is both an interstate and an international river. The Rio Grande Compact Commission, with Texas, New Mexico and Colorado representatives, manages water sharing among the states. Once the Rio Grande becomes an international boundary with Mexico, an international treaty and commission governs water sharing by the two countries.

These rivers flow into estuaries, bays and eventually the Gulf of Mexico. The inflow of fresh water from these rivers mixes with the saline gulf waters, creating rich, diverse aquacultures supporting economically important populations of fish, shrimp and oysters. Many of these creatures can spawn and hatch only in these semi-saline waters, later migrating out to the deep gulf to grow to adulthood.

According to the National Wildlife Federation, “95 percent of the Gulf’s recreationally and commercially important fish and other marine species rely on estuaries during some part of their life cycle.”23 TPWD estimated that the 2006 shrimp catch was valued at nearly $87 million.24 Texas bays also contribute to the state’s tourism industry and in all generate more than $2.5 billion in economic activity each year.25 In 2004, Texans consumed 6.3 million acre-feet of surface water. Exhibit 11 identifies the use of this water by sector.

Exhibit 11

Texas Surface Water Use, 2004

pie chart showing percentages of surface water used by sector

(Texas Surface Water Use, Text Alternative)


While Texas’ rivers provide water for human, animal and industrial uses, groundwater supports irrigated agriculture and is increasingly important for human consumption. Since the 1970s, according to TWDB data, groundwater consistently has accounted for more than half of all Texas water use.26

Groundwater exists in underground formations called aquifers. Texas has nine major aquifers and 21 minor ones (Exhibit 12).

Aquifers depend entirely on rainfall for replenishment. In the arid West and semi-arid Western-Central area of Texas, replenishment rates are not keeping up with pumping. The problem is particularly acute in the Ogallala aquifer, which lies beneath portions of eight states, including much of the Texas Panhandle. Rainfall is limited in the area, and large areas of the surface are covered by a layer of nearly impermeable caliche, preventing much of the area’s rainfall from percolating through the caliche into the aquifer.27

Even so, use of Ogallala water is substantial; in 2000, for example, about 65 percent of the estimated 10 million acre-feet of groundwater used in Texas came from this aquifer.28

Exhibit 12

Major Texas Aquifers

pie chart showing percentages of ground water used by sector

(Major Texas Aquifers, Text Alternative)

In 2004, groundwater supplied 59 percent, or 9.2 million acre-feet, of Texas’ water. 29 Of that amount, almost 80 percent was used for agricultural irrigation. Texas cities relied on groundwater for 36 percent of their water supplies, accounting for 15 percent of total groundwater use (Exhibit 13).The remaining 5 percent of groundwater use was for manufacturing, mining (generally in the oilfield), livestock and steam for electricity generation. TWDB projects that the amount of groundwater that can be used under current permits with existing pumping facilities will decrease by almost a third in the next 50 years.30

Exhibit 13

Texas Groundwater Use, 2004

Texas map showing the locations of the major aquifers

(Texas Groundwater Use, Text Alternative)


Texas’ surface water – all the water in its streams, rivers and lakes, with some exceptions – is owned by the state. TCEQ issues permits to applicants on a “first-in-time, first-in-right” basis. A permit does not guarantee that water will be available; it only means that the permit holder is in line to use it. Owners of the most senior rights – that is, the oldest permits – can take whatever water is available up to the limit specified in the permit. The remaining water is apportioned in sequence to the holders of junior rights. When drought conditions reduce the amount of available surface water, generally only senior rights can be exercised.

To acquire a water permit an applicant must prove that water is available, that the use is consistent with state law and, occasionally, that a defined amount of water has been obtained consistently from a known source, even if that use pre-dates the permit system. In fact, of the almost 10,000 permits active today, 98 date back to the 18th and 19th centuries.31

Texas has an international treaty with Mexico regarding the Rio Grande’s water. Because the international border lies in the middle of the river, a 1944 agreement controls how its water should be divided between Mexico and Texas. During the past 15 years, however, many disputes have arisen over the quantity and timing of water transfers.32

In September 2005, Texas and Mexico settled some elements of a long-standing dispute over water use in the Amistad and Falcon reservoirs on the Rio Grande, with Mexico repaying 1.5 million acre-feet of water it owed Texas citizens. Although the legal aspects of the treaty dispute between the countries are settled, some Rio Grande Valley farmers and irrigation districts are pursuing damage claims in international courts, alleging that Mexico’s withholding of water caused them economic harm.33

Access to Texas groundwater belongs to the owners of the land above it. Under the legal “rule of capture,” landowners are entitled to pump as much groundwater as they can, as long as the use is not malicious or wasteful, even if pumping it deprives other landowners of water. Once pumped, groundwater may be used or sold as private property.

The state’s 89 groundwater conservation districts (GCDs, or occasionally GWCDs), some of which cover single counties and others multiple counties, were created under state laws and are governed by locally elected board members. GCDs may develop well-spacing rules, pumping permits, fees and overall pumping limits within their districts. Under Texas law, GCD enforcement of its rules is one of only two ways to limit groundwater pumping in an area; the other is a judgment in Texas courts, although the Edwards Aquifer Authority can restrict pumping within its statutory boundaries.

Exhibit 14

Groundwater Management Areas in Texas

Texas map showing the locations of ground water management areas

(Groundwater Management Areas, Text Alternative)

Separate from but overlying the GCDs are the state’s 16 groundwater management areas (GMAs) that generally encompass entire aquifers (Exhibit 14). The GMAs exist to bring the GCDs within them together to determine the region’s anticipated groundwater use, supplies and demands. TWDB then uses these estimates to aid in planning for Texas’ future water resources.34

Texans are employing several strategies to extend existing fresh water supplies. The first and, in some ways, easiest strategy is simply to reduce consumption through conservation. Farmers in the High Plains have greatly reduced their groundwater consumption in the past 40 years by employing efficient drip irrigation systems; reducing evaporation losses by piping instead of trenching; and weaning themselves off irrigation altogether through dryland farming.35 Although these techniques have conserved water, the equipment involved generally is expensive, and less water may increase the risk of crop failure.

Many if not most urban water utilities have conservation programs designed to reduce home usage via low-flow shower heads, low-volume toilets, xeriscaping (using low-water landscape plants), rain harvesting and drought restrictions. Industrial users are encouraged to reuse water, often by using “gray water” (that is, once-used water, such as water with non-hazardous contaminants like soap or food particles) when drinking water is not required, such as watering golf courses.36

Other strategies include using groundwater and surface water together when appropriate, and removing water-loving plants and brush such as juniper and mesquite. One strategy suggested by planners but not widely implemented is dredging reservoirs to increase their capacity. However, the cost of dredging is roughly twice that of building a new reservoir.37

A new source of Texas water is desalination. Desalination is a promising albeit expensive strategy to reclaim fresh water from brackish or salt water. “Desal” technology is relatively straightforward. The most common is reverse osmosis, or RO. Source water is pumped under extremely high pressure through a series of membranes resembling thick rolls of wax paper. The membranes are capable of capturing salt molecules, viruses, bacteria and other microscopic organisms and molecules. Because the water is so highly pressured, RO plants consume large amounts of energy and thus are vulnerable to rising energy costs. The residual waste is generally highly toxic because of its high salt content. Injection wells usually are used to dispose of the residue deep underground, where it cannot migrate into other water sources. Desal plants near coastal areas often pipe the residue far out into coastal waters.

The potential for brackish groundwater as a future resource has received renewed attention in efforts to plan for meeting future water needs. An estimated 2.7 billion acre-feet of brackish groundwater is available in the state, and with RO costs coming down, efforts to access that water have gained importance in recent years. The Legislature appropriated state funding in 2005 to support desalination demonstration projects.38

In August 2007, the city of El Paso opened a large desalination plant capable of supplying the city and the nearby U.S. Army installation at Fort Bliss with 27.5 million gallons of drinking water daily (or 30,800 acre-feet per year), about 30.8 percent of its 2006 daily usage.39 The water comes from the mostly brackish Hueco Bolson aquifer in West Texas, and is desalinated by RO. The cost of the resulting water is expected to be $1.65 per 1,000 gallons, which compares with current retail rates of a minimum $1.68 per 1,000 gallons in El Paso, $0.93 in Austin, $1.41 in Dallas and $3.23 in Houston.40


Water used for human consumption in municipalities, whether taken from surface or underground sources, is piped to water treatment plants. These plants filter and chemically treat the water to bring it to drinking water standards. From the treatment plants, the water is then pumped through water delivery pipes to the end users. Treatment and distribution is an energy-intensive process – up to 80 percent of treatment costs are due to electricity consumption.41

Treated drinking water is distributed by various entities including municipal water services, in most urban areas; “municipal utility districts” (MUDs), authorized by TCEQ at the request of property owners (usually in suburban subdivisions); and by private water supply companies. Federal laws including the Clean Water Act and the Safe Drinking Water Act set water quality standards for such water systems. In Texas, TCEQ enforces these standards.


The Federal Water Pollution Control Act of 1972, better known as the Clean Water Act, authorizes water quality programs; imposes federal effluent limits and state water quality standards; and requires permits for the discharge of pollutants into navigable waters.42

Under the terms of the act, states must establish standards for how their water bodies are to be used. The Texas Surface Water Quality Standards define water use as aquatic life use, contact recreation, public water supply and fish consumption. About 46 percent of Texas’ water bodies were not in compliance with the state’s water quality standards in 2000.43 Non-compliance requires state and local officials to determine the reasons for and sources of pollution and develop a plan to correct the situation.


TWDB estimates the Texas population will rise from 21 million in 2000 to 46 million by 2060.44 TWDB expects demand for water to increase by 27 percent, from 17 million acre-feet in 2000 to 21.6 million acre-feet in 2060. At the same time, the amount of water that can be stored in the state’s existing reservoirs is expected to decrease by 18 percent, from 17.9 million to 14.6 million acre-feet, because of increased sediment in the reservoirs.45

Rivers and streams are not limitless resources, and their contribution of freshwater to coastal estuaries and bays is critical to maintaining the health of these uniquely valuable ecosystems. Even before they reach the coast, rivers themselves need to contain certain volumes of flowing water to be able to support fish and wildlife and the surrounding environment.

The 2007 Legislature passed House Bill 3 to determine how much instream water and coastal inflows, or “environmental flows,” are necessary to maintain viable river and bay systems. State leaders will appoint groups of stakeholders for each river and bay system. These groups will work with scientists and experts to develop recommendations that will ensure the ecological soundness of the water systems. Their recommendations will be submitted to TCEQ by September 1, 2009.46

Aquifers can be depleted if pumping exceeds recharge, a situation now occurring in several aquifers in the state. GCDs have limited powers to remedy these situations.

Water Planning

In 1997, Texas embarked on a new approach to water planning with the passage of Senate Bill (SB) 1, which divided authority for water planning among 16 regional water planning groups (RWPGs), with their boundaries drawn to reflect major basins and communities of interest. Each group comprises representatives of every major water interest, including local governments, industries, agriculture, small businesses, environmental organizations, electric utilities, river authorities, water districts and the public.

Each RWPG is responsible for measuring its current water use and projecting population changes and future water use; assessing water supplies; identifying the location and amount of water surpluses and demands; evaluating water management strategies; receiving public input; and creating a plan to meet future needs. RWPGs may also submit recommendations for any changes in regulations, administration or statutes needed to ensure that the plan succeeds.47

RWPGs must submit their plans to TWDB once every five years. TWDB then compiles the regional plans into a single State Water Plan. The 2007 version of this plan is the second produced under the S.B. 1 planning process. Water projects and the financing needs of approved plans are eligible for state funding if and when such funds become available.

TWDB’s 2007 Water Plan identifies 4,500 water management strategies that could add 9 million acre-feet per year to the Texas water supply. TWDB estimates that the capital costs of these projects – which include building new reservoirs, an expensive and controversial proposition, as well as desalination plants, conservation measures and increased transfers between river basins – could cost $30.7 billion in current dollars.48

TWDB also estimates that the cost of not implementing these strategies, assuming widespread drought conditions, would be about $9.1 billion in current dollars in 2010 and $98.4 billion in 2060. Without planning for expected population increases now, a drought in 2060 could mean that 85 percent of Texans would not have enough water to sustain their current levels of use.49 Whether that level is necessary – and sustainable – is a question for all Texans.

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