Lake vs. Reservoir

The State of Texas has hundreds of water bodies - from small farm tanks to huge reservoirs - but within the state's 269,000 square mile area, there is only one naturally-formed lake - Caddo Lake on the Texas Louisiana border - the rest are man-made reservoirs.

According to the Texas Parks and Wildlife Department, there are more than 175 registered reservoirs in the state. These reservoirs have been built by the US Army Corps of Engineers for the federal government or by state, county, city or district entities.

Flood Control vs. Water Supply

Reservoirs serve a number of functions: they lessen the potential of flooding by catching water behind a dam that may be released later in a controlled manner. They store water for human consumption such as drinking water, irrigation for food crops, as well as commercial and industrial needs such as manufacturing and electric generation. They also allow great outdoor recreational opportunities.

The Brazos River Authority System of reservoirs includes both flood control and water supply reservoirs. Eight flood control reservoirs were built and are run by the US Army Corps of Engineers and three water supply reservoirs -- Lakes Possum Kingdom, Granbury and Limestone -- were built and are owned and operated by the Brazos River Authority The BRA pays a fee to the federal government to store water in the Corps reservoirs.

The main purpose of a water supply reservoir is to capture and store water during wet times so that water is available during dry times or drought. Through a permitting process with the state, the BRA provides water supply for drinking, household use, agriculture, mining and industry.

What is the difference between a federal US Army Corps of Engineer reservoir and a Brazos River Authority-owned reservoir?

There are two major differences between a Corps reservoir and a BRA reservoir: the type of dam holding back the reservoirs' water and lakeside access to that water.

The dams that hold back water in the flood control reservoirs constructed by the Corps are built specifically to hold back flood waters within their watershed area. This means that the dam itself towers over the normal level of the reservoir.

The dams that hold back water for water supply reservoirs are smaller, with the water supply stored there rising to the top of the dam when the reservoir is at capacity.

Why is this important?

Because flood control dams are built to temporarily hold back flood waters, homes and permanent structures cannot be built within a potential inundation or flood area. As a result, the Corps of Engineers do not allow residents to build their homes close to the water and lakeside docks are not allowed.

Unlike Corps reservoirs, the BRA allows lakeside owners to build private on-water facilities or docks directly on the water. The BRA also provides lakeside property owners the opportunity to access water from the reservoir for landscape watering purposes. Both private docks and landscape water access are made available by obtaining a permit from the BRA.

Living on a water supply reservoir

Living on or near a Texas reservoir comes with both privileges and responsibilities. Boating, fishing and hunting within steps of your home are some of those benefits.

Along with these benefits come several important responsibilities. The water stored in these reservoirs is most likely the same water that will flow from your home faucets. Maintaining the ecological health of the lake is extremely important to the health and well-being of our community. Properly maintaining septic systems at your home, regularly servicing boat motors, and careful application of fertilizer and herbicide products, and refraining from dumping grass clippings and pet droppings into the reservoir will help insure the reservoir remains safe for drinking water.

Constant lake levels vs. fluctuating lake levels

There are few, if any, constant levels reservoirs in Texas. Those lakes that are constant were most likely built specifically to serve as landscape structures. Both flood control and water supply reservoirs are made to fluctuate with change in rainfall, evaporation rates, and water use.

During times of severe drought, lake levels can drop significantly. As water demands increase, water levels will rise and fall more often and to a greater degree than seen in past years. Those that live on a canal may find that during times of drought and high water consumption this fluctuation could mean that canals may not have adequate water levels to move a moored watercraft into the main body of the lake.

If you choose to live on a water supply reservoir, you must be aware that it is normal for lake levels to fluctuate possibly dropping as much as 33 feet.