Senator Eliot Shapleigh - El Paso, Texas

Rio Grande

Even as the state shrugs off climate change in its long-term water planning, Central Texas' largest water project is addressing it.

A science review panel for the $2 billion project, which would ship Colorado River water to San Antonio for 80 years, has told the Lower Colorado River Authority and the San Antonio Water System to keep climate change in mind as they determine whether to pursue the project. The two agencies are in the middle of a $42 million feasibility study.

Last year, the Highland Lakes, the reservoir and flood control system critical to Central Texas water planning, lost more water to sun and wind than was consumed by Austin, and evaporation could increase by at least a quarter within the next century due to climate change, according to the head of the science review panel. (On average, the lakes lose about 52 billion gallons of water a year to evaporation.)

"It's the only major water planning effort I know of that's fully incorporating climate change into its analysis," said Andrew Sansom, the panel's chief.

LCRA General Manager Joe Beal said the increase in average temperatures could have drastic consequences for the river and its lakes.

For example, a one-degree temperature increase would lower the effectiveness of lakes designed to be heat sinks for power plants, such as Lake LBJ.

"If you increase temperature by a degree, there's less heat that a lake can take," Beal said. "You need to back down your power plant."

Preliminary results from a University of Texas study suggest that temperatures across Austin could increase by four degrees in the next 50 years.

But he added that the upshot of climate change on water availability is hard to predict since climate change could lead to more hurricanes, which provide water for the Colorado River.

If temperatures rise and droughts become longer, the LCRA would accelerate its water conservation and development work, Beal said.

The LCRA could pipe downriver water back up to the Highland Lakes, aggressively urge Austin to reuse its treated sewage water or build desalination facilities.

The current state water plan, published this year, largely ignored climate change.

"When considering the uncertainties of population and water demand projections, the effect of climate change on the state's water resources over the next 50 years is probably small enough that it is unnecessary to plan for it specifically," said the plan, which sets goals for conservation and water use in the next half-century.

"The reality is, from a statistical perspective, the certainties relating to climate change are much less than ones relating to population change, water demand or policy issues," explained Bill Mullican, the deputy executive administrator for planning at the state's water development board.

The next water plan, slated to be published in 2012, would address climate change in greater detail, he said.

"There will be a much more thorough vetting of potential impacts of climate change on water supplies for the state," he said.

A proposal by state Sen. Eliot Shapleigh, D-El Paso, calls for the state water development board to study the consequences of climate change on the Rio Grande. The bill passed the Senate, and with two weeks left in the legislative session, it sits in a House committee.

"Climate change is a very uncertain thing," said Warren Pulich, a research scientist at Texas State University's River Systems Institute who also serves on the LCRA-SAWS project science review panel. "But in the planning process, you do need to consider as far as possible as many eventualities as might occur."