Water advisory committee looks at minimum storage level for Highland Lakes

Members of the Water Management Plan Advisory Committee on Tuesday agreed on the components to be considered when determining the minimum combined storage level allowed in lakes Travis and Buchanan during a repeat of the worst drought in recorded history, known as the Drought of Record.

The minimum combined storage level is the lowest level the lakes are allowed to reach during the computer simulations, or models, used to help update the plan that determines how water is used from lakes Buchanan and Travis, the basin's water supply reservoirs. The computer models simulate how different management techniques would affect water supply through a repeat of the dry weather conditions that caused the Drought of Record. The combined minimum storage level is used as a safety net during severe drought.

Committee members want the minimum combined storage level based on one year's annual supply for firm water customers. Firm water customers include cities and industrial facilities that buy water from LCRA that should be available through a repeat of the Drought of Record. Tuesday, members agreed that the following factors should be considered when determining how to calculate this minimum combined storage amount:

• Water needed to meet projected firm customer demands in 2020 (considering different levels of potential drought management measures).
• Water remaining in the lakes' dead pools. This is the level at which water from lakes Buchanan and Travis can no longer be released by gravity through the respective dams.
• Evaporation from the Highland Lakes.
• Water to help meet critical environmental needs of the river and Matagorda Bay.
• The amount of water upstream rivers, streams and other tributaries could potentially provide for storage in the lakes during dry or drought conditions. This water is called inflows.

On Tuesday, committee members also viewed a presentation of the criteria for making a declaration that a drought is potentially worse than the Drought of Record. This is important because if LCRA's Board of Directors determines that a drought has reached this point, interruptible agricultural customers are cut off and firm water customers are required to reduce water use by 20 percent.

The standards for determining if a drought is worse than the 1950s Drought of Record are based on the duration and intensity of a drought and the amount of water in the two lakes. LCRA is considering modifying the standards in this plan update based on lessons learned in past droughts. The changes would be aimed, in part, at making the standards easier for the public to follow and understand.

The diverse 16-member advisory committee that is helping LCRA update the plan is composed of members who represent the major groups that depend on the Highland Lakes. It has been meeting since July and is scheduled to finish its work in June.

The lakes help provide water for 1.1 million people in Central Texas as well as water for farming, industry and the environment. The plan contains triggers that determine who must reduce water use, and when, in times of drought. The triggers are generally based on the combined storage of lakes Travis and Buchanan.

The advisory committee is tasked with providing input to LCRA on how to improve water management strategies outlined in the plan to address needs in the basin, including those of cities, industry, agriculture and the environment elements. Once the LCRA Board of Directors approves an updated plan, it goes to the Texas Commission on Environmental Quality for a final decision.

The committee's next meeting is April 26 at the Riverside Conference Center in Bastrop. Committee member and LCRA staff will likely meet for a work session before then. For more information on the Water Management Plan or the Advisory Committee please go to www.lcra.org/watermanagementplan.