LCRA has the rights to more than 2.1 million acre-feet of water per year (AFY). These rights -- based mostly on surface water permits issued by the State of Texas -- include the right to divert and use up to 1.5 million AFY from lakes Buchanan and Travis and 636,750 AFY under downstream run-of-river water rights from the Gulf Coast, Lakeside, Garwood and Pierce Ranch irrigation operations.

As of January 2008, LCRA’s total commitments by contract or Board resolution for firm water* supply were about 507,000 AFY, excluding any contractual obligations under the LCRA-SAWS Water Project. Maximum use of firm water supplies in recent years has been 143,600 AFY. (For the latest water supply data see the "quarterly report" in the sidebar to the right.)

* Firm vs. interruptible water: Water supplies managed by LCRA are divided into "firm" and "interruptible" stored water. Firm water is available even during a severe drought. Cities, industries and electric power plants rely on firm water supplies. During water shortages, interruptible water, which is mostly used for agriculture, is subject to rationing or curtailment first -- before firm water supplies.

A managed water system
LCRA uses the lakes and river as a system to conserve and convey water supplies according to a plan developed by water supply experts and approved by the state of Texas. Following this water management plan makes it possible to supply drinking water for about 650,000 people, as well as water for industry, energy, and recreation; for irrigating rice and other crops; and for preserving a healthy ecosystem along the lower river and in Matagorda Bay.

Water is released from lakes Buchanan and Travis when springs and tributaries that feed into the lower river do not provide enough to meet downstream needs, including the need for fresh water in Matagorda Bay on the Gulf Coast. The bay and estuaries depend on fresh water from the Colorado River to maintain a healthy habitat for fish and other aquatic life.

The volume of water released from the lakes for this purpose depends on how much water is stored in the Highland Lakes and the amount flowing to replenish the lake and river system. In normal times, the releases are meant to maintain an ideal habitat. If the lakes are low, the releases are intended to keep salinity from reaching critical levels. How much fresh water does the bay require? That is the subject of a new interagency study.

Times of drought
When a major drought occurs there may not be enough water for all purposes. During severe dry periods, the lower Colorado River may flow at greatly reduced rates and lakes Travis and Buchanan may drop significantly from their storage capacities.  Check the Daily River Report or the Water Watch graphic to find out how much water is in storage currently.

The water management plan describes how to allocate water during water supply shortages. It directs the curtailment of interruptible water supplies so that demands for firm water are fully met. LCRA takes action at key points as the lake levels drop.

One of the first steps is to ask all customers -- those with interruptible and firm water supply contracts -- to voluntarily reduce water use through sound conservation measures. If the shortage intensifies, LCRA may call for mandatory conservation measures. Extremely low levels would trigger the cutoff of all stored water releases for agricultural irrigation. Although that has not been necessary in the past, the likelihood increases as demand increases to use water for other purposes.

That is one reason LCRA is working with the San Antonio Water System (SAWS) to explore whether a joint water project could increase the amount of water supply available in the lower Colorado River region at a reasonable cost and without harming the environment. The LCRA-SAWS Water Project is an outgrowth of the state's regional planning process. The Lower Colorado Regional Water Planning Group has included the interregional project as part of its 50-year water supply plan.