Water School

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.Possum Kingdom Lake covers an area of 16,716 acres with 219 miles of shoreline. The reservoir holds approximately 556,340 ...

DeCordova Bend Dam and Lake Granbury were constructed by the Brazos River Authority and are maintained and operated by the BRA as a source of water supply.Construction of the project began in December 1966 and was completed in September 1969. The reservoir provides 129,011 acre-feet of storage capacity for conservation of flood and storm waters to meet requirements of municipalities, industries, agriculture and mining.  The reservoir has a permitted yield of 64,712 acre feet. ...

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 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 reservoir is supplied for similar use at a NRG steam-electric plant just...

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.

Floodgates are solid metal barriers in a dam that can be opened to release flood waters downstream.

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 plan...

A wildlife management exemption to Texas water rights allows property owners to build and maintain a dam or reservoir of not more than 200 acre-feet of water on qualified open-space land for the purpose of providing water to indigenous wildlife.

A dam is a structure designed to hold back water in a lake, river, stream or other waterbody. Large dams typically include gates or other outlet devices 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 reservoir through the gates is called a spillway.There are several styles of dams used for different purposes to meet specific conditions at the dam site.  The design of the dam is in...

While the process may vary for each location, here’s a general outline of how a reservoir goes from idea to reality.Once a need for water in an area is established, a site for the reservoir must be chosen. Several factors go into this decision, including nearness to a source of demand, a feeder supply of water (such as a river or creek), the geological suitability of the area and engineering constraints. Other factors considered could include impact on the environment, the local population...

Mean sea level is the average height of the ocean’s surface, between high and low tide. It is used as a standard in reckoning land and other elevations such as lake levels. A lake’s conservation pool will be measured as a certain number of feet above mean sea level.

Periodically, officials conduct surveys of reservoirs within the Brazos River 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 reservoir’s depth is the distance from the 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.Surveys use a combinat...

Texas streams and rivers are in constant motion and the waters they pour into our reservoirs carry with them a continuous but varying amount of sediment.When the water is slowed or stopped as it runs into a reservoir or by a dam, the sediment drops to the bottom. This sediment builds up year after year and at some point, fills the reservoir to a point it can no longer continue to serve its purpose in flood control or water supply. Without expensive dredging, this would be the end of the res...