Despite a common misconception, there are very few “constant level lakes,” and none operated by the Brazos River Authority.  A constant level lake is one that is artificially managed to remain at a specific level essentially by using another source of water to replenish losses due to evaporation, etc.  

Several factors can affect a lake’s level and only some are within human control. The chief factor that is not controllable is the impact of climate.  Evaporation is a constant, natural part of the water cycle that causes the liquid form of water to change into gas or vapor and move into the atmosphere reducing the amount of  water in a lake.

During periods when outdoor temperatures rise, the rate of evaporation increases. During periods of drought the effect is even more dramatic.

As temperatures rise, increased demand by residents, agriculture, cities, industry, power plants and others on water stored can also draw down a lake’s level.  This impact is exacerbated during periods of extended drought.

Though it can be frustrating for those who live near Texas lakes or turn to them for recreation, dropping lake levels during a drought are also a sign that a reservoir is successfully meeting one of its basic obligations: supplying water to thirsty Texans during a time of need. 

Possum Kingdom Lake, located on the main stem of the Brazos River northwest of Fort Worth, was the first water supply reservoir constructed in the Brazos River basin. Located in Young, Palo Pinto, Stephens, and Jack counties, the construction of the Morris Sheppard Dam was begun in 1938 and completed in 1941 with the aid of the Works Progress Administration Program.

Named for the United States Senator who was instrumental in obtaining funding for the project, the Morris Sheppard dam is 2,700 feet long and 190 feet high. The dam consists of nine crest "roof weir" type gates, each approximately 74 feet long and 13 feet high for the passage of floodwaters. Each gate passes approximately 9,600 cubic feet per second (cfs) of water when open.

The Morris Sheppard dam is a hydro electric generating facility with two 11,250 kilowatt generators. Categorized as a "peaking plant," the generators can supply electricity during high demand periods.

Possum Kingdom receives an estimated three million recreation visitors annually. Major activities on the lake include fishing, water skiing, and scuba diving. The lake has public fishing piers, five public boat ramps, public access areas for picnicking, and a total of 400 primitive camp sites.

To view a copy of the Possum Kingdom Lake permit, click here

De Cordova Bend Dam and Lake Granbury were constructed by the Brazos River Authority and are maintained and operated by the Authority as a source of water supply.

Construction of the project began in December 1966 and was completed in September 1969. The project provides 129,011 acre-feet of storage capacity for conservation of flood and storm waters to meet requirements of municipalities, industries, agriculture and mining.  To view the state permit establishing Lake Granbury, click here

The lake was built without use of any tax money, having been financed entirely with revenues from sales of water by the Authority. The principal revenues used to finance the project are provided under a contract with TXU Electric Company for purchase of water for industrial use, including cooling water for a natural gas-fired steam electric power plant on the lake and the Comanche Peak nuclear power plant near Glen Rose. The lake also furnishes raw water for the Authority’s Lake Granbury Surface Water and Treatment System, which supplies treated water to customers in Hood and Johnson counties. 

The lake has five public access areas for picnicking and fishing. Four of these areas have primitive camping sites. 

Lake Limestone, located on the upper Navasota River in Limestone, Robertson and Leon counties, is a water supply reservoir built by the Brazos River Authority in 1978.

Construction of the reservoir was made possible through the sale of water to Texas Electric Utilities for "cooling water" to be used by their lignite-burning electric plants in the area.  To view a copy of the Lake Limestone state permit, click here

Water from the lake is supplied for similar use at a NRG steam-electric plant just east of the lake and a Texas Municipal Power Agency power plant located near the Navasota River 50 miles downstream.

The waters of the lake are open for public use for all types of water-based recreation. The Authority provides free public access areas at various locations around the lake for boating, swimming, fishing and other recreational activities.

Lake Limestone was formed by the construction of Sterling C. Robertson Dam. Constructed of earth and concrete, the dam runs 8,395 feet.

The Robertson Dam stands 72 feet tall with a emergency spillway measuring 3,000 feet. The service spillway is made of concrete and houses five "tainter" gates for water release. Each gate measures 40 x 28 feet. The depth of the lake near the dam is 43 feet.

When full, the lake covers a surface area of 12,680 surface acres and holds back 225,440 acre-feet or 73.5 billion gallons of water.

The project was built entirely without use of any tax money. Funding for the reservoir was financed by revenues from the sale of water.

A spillway part of a dam that is designed to allow water to flow freely over the dam during floods. Spillways may be used on dams with floodgates as an additional means to control release of water during flooding.  A spillway may also be used as the main area of water release from a dam, allowing water to flow through the spillway only when the reservoir is full. 

Maps of Authority lakes may be found online by visiting each lake’s Web page: Possum Kingdom, Granbury and Limestone  Printed maps of all the lakes are available free of charge at each lake office or by calling the Public Information Office at (888) 922-6272.

The fee for a dock basically allows the permit holder to build and maintain a permanent structure over Authority property (the lake bed). It also gives the Authority the ability to ensure that the docks that are built are safe. The permit fee is not a tax, but rather a fee for a service.  For a dock permit application, click here. 

Lakeside property owners can build docks on the lake if they complete an Authority On-Water Facilities Permit, pay the relevant fees and the Authority approves the permit. Lake regulations set requirements property owners must meet when building a dock.  Details on these regulations may be found in Section 7 of the regulations.

The US Army Corps of Engineers (Corps) operates eight flood control reservoirs within the Brazos River basin that, through a contract with the federal government, also serve as water supply impoundments for the Brazos River Authority system of reservoirs.

Lakes Proctor, Whitney, Aquilla, Belton, Stillhouse Hollow, Georgetown, Granger, and Somerville store water for use by municipal, agricultural, industrial and mining use.

Similar to the Authority’s three water supply reservoirs, water contracts are available to lakeside owners for the purpose of watering lawns and livestock. These contracts are available through the Brazos River Authority with approval by the Corps of Engineers.

Allens Creek Reservoir is a planned water storage lake permitted for construction on Allens Creek, a tributary of the Brazos River, in Austin County. The permit to build the lake was originally issued to Houston Lighting and Power (Reliant Energy) in 1974 by the Texas Natural Resource Conservation Commission, now known as the Texas Commission on Environmental Quality (TCEQ).

The reservoir was originally to have served as a cooling lake for a nuclear power plant. When Reliant Energy abandoned plans to construct the nuclear power plant at the Allens Creek site in the 1980s, the property was purchased by the City of Houston and the Brazos River Authority with the purpose of building a water storage reservoir.

The new reservoir will provide water to meet the future needs of the City of Houston and surrounding communities. When complete, the reservoir will supply 92,000 acre-feet of water supply and access to water recreation for the area. Swimming, boating, fishing and camping facilities will be available to the general public. Construction is expected to begin by 2018.

The height above mean sea level that water in a reservoir has reached. Brazos River Authority and U.S. Army Corps of Engineers lakes are actually reservoirs, or parts of the Brazos River basin impounded by dams. (A free-flowing river is measured in stages, that is, by depth from the river bed to the surface.)

As the name implies, water supply lakes are built primarily to provide a place to store water for Texas residents, communities, businesses, agriculture, industry and others who all depend on water to survive and thrive. Such lakes are especially vital during periods of drought, when other sources of water may be limited.  Many of Texas’ flood control lakes serve a secondary purpose as a water storage facility.  However, reservoirs designed for water supply, do not necessarily also provide flood control.

Water supply lakes within the Brazos River Authority system are lakes Possum Kingdom, Granbury and Limestone.  Flood control lakes that also provide water supply for the Brazos basin include lakes Somerville, Proctor, Stillhouse Hollow, Belton, Georgetown, Granger, Aquilla and Whitney.

A dam is a structure designed to hold back water in a lake, river, stream or other water body. Dams typically include gates that can be raised or lowered, opened or closed to allow variable amounts of water to pass downstream or leave the lake. The path the water takes to leave the lake through the gates is called a spillway.

There are several styles of dams used for different purposes. 

• An arch dam is made of masonry or concrete that is convex towards the upstream. Its stability depends on the arch, which transfers the water pressure to abutments on each end of the dam.
• A buttress dam has a watertight face upstream supported by buttresses along its downstream side.
• A coffer dam is a temporary watertight enclosure that is pumped dry to expose the bottom of a water body so construction can be done.
• A gravity dam is made of concrete or masonry and depends on its weight for stability. A variation of this is a crib dam, which has chambers made from wood or other material and those chambers are filled with stone or heavy materials. 
• An embankment dam is built of fill material such as earth or rock. It has sloping sides, with a length greater than its height.
• A weir is a dam in a river or stream that raises the water level for a mill, creating a fish pond or other smaller-scale uses.

A reservoir may be a pond, lake or basin, either natural or man-made, used for the storage, regulation and control of water. 

Releases are made for several reasons including water supply for users near the lake and downstream, to pass through water released from another system reservoir, or to refill storage in a downstream reservoir.

For a look at current lake levels, click here.   

Natural lakes have been a rare commodity in Texas. In fact, the state had only one natural lake, Caddo Lake in East Texas, that was formed by a log jam.  A permanent dam was installed at the lake in the early 20th century.

A large number of the state’s remaining lakes were made in response to the occasional propensity of Texas’ usually tranquil rivers to flood during heavy rains.

Texas’ early history is filled with accounts of devastating floods causing loss of human life and destroying livestock and property, particularly along the Brazos. As a result, in the 1930s and 40s officials began building dams along Texas rivers to create flood control reservoirs that would absorb the floodwaters and alleviate damage and loss of life.  

 Possum Kingdom Lake (left) was built during this period. Momentum for such flood control projects picked up during the 1950s and the US Army Corps of Engineers was tasked with building several more lakes for flood control over the next several decades. Ironically, the worst drought of record for Texas took place during the 1950s, prompting emphasis on a second priority for these lakes: water supply . 

While the process may vary from lake to lake, here’s a general outline of how a reservoir goes from idea to reality.

Once a site is selected, hydrologists calculate early estimates of reservoir capacity and water supply availability to determine the lake’s yield. After these preliminary sighting and feasibility studies are complete, requests for a permit to impound water of the state is submitted to the Texas Commission on Environmental Quality.  When permits are approved and complete, officials begin acquiring the land to be covered with water.

Once land is secured for the new reservoir, a series of pre-construction studies are conducted and state and federal permits are acquired. A final dam design is completed based on the various studies and once the permits are obtained, the dam is built and water is impounded.

The lake-building process can take several years or even decades. Throughout the process, officials hold public meetings to inform and obtain input from the public.

The great majority of our lakes in Texas were built to help tame the state’s rivers and streams, which from time to time would swell beyond their banks and cause devastating floods. Such was the case with the Brazos River. History books record numerous destructive floods took place in the Brazos basin before a series of dams was built along its length to create reservoirs to hold periodic flood waters.

Periodically, officials conduct a survey of lakes within the Brazos basin to determine each lake’s volume. As part of that work, survey crews determine each lake’s depth (in feet). Do not confuse this measurement with lake level, however.

A lake’s depth is the distance from the lake’s bottom to the top of the conservation pool, the point where the lake is considered full. The lake level is the number of feet the surface is above mean sea level. 

Crews use a combination of GPS technology and sonar to find the lake’s depth at various points to get an average to determine volume. The sonar sends sound waves to the lake bottom at different frequencies, and the results are compared to help also determine how much sediment has collected. The surveys also find each lake’s deepest point, which is typically near the dam.

Texas streams and rivers are in constant motion and the waters they pour into our lakes carry with them a continuous but varying amount of sediment.

When the water is slowed or stopped as it runs into a lake or by a dam, the sediment drops to the lake’s bottom. This sediment builds up year after year and at some point, fills the lake to a point it can no longer continue to serve its purpose in flood control or water supply. This would be the end of the lake’s effective “lifetime.”  The average life of a lake in Texas is considered to be about 100 years. 

The conservation pool of a reservoir is a specified amount of water dedicated to water storage. This water is to be used to meet water needs, including municipal, domestic, agricultural, industrial, and recreational.

A flood pool is a specified area within a flood control lake and the surrounding land that may only be inundated during periods of flooding. This allows the flow of waters to be regulated and released in a safe manner.