Water – A Valuable Resource
Water conservation and a focus on responsible management have become key components of water planning in Texas. The disparity between reduced water supplies and rising water demands creates an increasingly difficult problem for planners.
Texas has 196 major reservoirs, a major reservoir being defined as an impoundment that currently has at least 5,000 acre-feet of storage capacity at its normal operating level. Of the 196 major reservoirs, 175 have a water supply function. The major reservoirs of the state vary in size from 5,200 acre-feet conservation storage capacity for the Upper Nueces Lake to 4,472,900 acre-feet for the Toledo Bend Reservoir, which includes both the Louisiana and Texas portions of the reservoir. The only natural lake in Texas is Caddo Lake. There are 6,736 reservoirs in Texas with a normal storage capacity of 10 acre-feet or larger. Caddo Lake’s conservation storage capacity is 129,000 acre-feet.
The annual rainfall in Texas ranges from as much as 55 inches in the eastern part of the state to as little as 10 inches in the western part of the state.
Almost 60 percent of water demands in Texas are satisfied from groundwater.
The average water usage rate within Region H varies from less than 100 gallons per person to more than 200 gallons per person. Demands vary according to the size of the community, geographic location, and type of water usage, such as residential irrigation.
An acre-foot of water is equal to over 325,000 gallons of water. The year 2000 water demand for the City of Houston was almost 350,000 acre-feet, or about 113,380,000,000 gallons of water!
An excessive groundwater withdrawal is the major cause of subsidence throughout the greater Houston area. One only needs to look at places such as Baytown, Texas City, and the Houston Ship Channel to see the effects of subsidence. By the late 1970s, subsidence had surpassed nine feet along the Houston Ship Channel and as much as five feet in the Texas City area, with a large part of Harris County experiencing at least one foot of subsidence.
Conservation efforts account for approximately 30 percent of the total water strategies presented in the 2007 State Water Plan.