As lakes Travis and Buchanan — Austin’s main reservoirs — continue to lose close to 1 billion gallons of water a day, forecasters are hopeful there is some relief on the way.
Going into the second-wettest season of the year, forecasters expect normal or above-normal rainfall, said Bob Rose, the chief meteorologist for the Lower Colorado River Authority, which manages the lakes.
“As we get more toward … October, we’ll begin to see more periods of rain, and I think this will continue into the winter,” Rose said. “This is not a drought-breaker or anything, but compared to the summer and last fall, I think we’ll be seeing more rain in the region.”
Austin typically sees more than 3 inches of rain in September and October, and Rose said projections call for at least that amount as the peak of the hurricane season approaches.
Still, Rose said, it would take “successive and significant rains” to pull Central Texas out of the drought, ideally upstream of Austin to refill lakes Travis and Buchanan. That would mean in excess of 15 inches, a rough number that can vary widely depending on where the rains falls, Rose said.
The area has seen three straight years of low rainfall, and the water flowing into the lakes is about a quarter of the expected amount. LCRA officials are trying to find new ways — including planning new reservoirs downstream of Austin — to deal with what could become the worst local drought on record.
Lake Travis is so low that some areas are almost completely dry. Sometimes Island, its mere presence a marker of a dry spell, has become a full peninsula jutting out into the lake, and every boat ramp on Lake Travis has been closed this year. Marinas are reaching far beyond their normal anchoring spots to find some water to sit on. A water treatment plant supplying a portion of the water for Cedar Park and Leander was shut down in mid-August because the lake dropped too low. For each of the past two years, the LCRA has taken the unprecedented steps of cutting off water to most downstream rice farmers.
“The drought continues to be persistent, and it continues to be intense,” said Ryan Rowney, the LCRA’s executive manager of water operations.
Lake Travis was last full in spring 2010, and Buchanan was full in fall 2007. Today, they are about 34 percent full, with 676,000 acre-feet of water total. (An acre-foot of water is enough for three average Central Texas households a year.) Lake Travis is about 7 feet above its record low set during the 1950s drought, the worst recorded in the area.
The two lakes have been losing about 3,000 acre-feet of water a day — 9 to 11 inches a week at Travis and about 5 inches a week at Buchanan. Some of the water is drawn out by cities and power plants. Some is released downstream to maintain the health of the river. And a good chunk is lost to evaporation; the six Highland Lakes lost 145,000 acre-feet to evaporation in 2012, for instance, almost as much as the city of Austin and its power plants used that year.
Even with normal rainfall, the National Oceanic and Atmospheric Administration’s Climate Prediction Center said the drought will persist in Central Texas through at least November. If conditions continue, record low lake levels are likely for late October or early November, Rowney said.
“That’s the worst-case scenario, but the worst case is what we’ve been tracking on for the past year or so,” Rowney said.
The river authority continues to look into temporarily lowering Lake Austin, long held at a fairly constant level even in times of drought, by 2 to 4 feet to take some stress off of the reservoir lakes.
The American-Statesman first reported the possibility of lowering Lake Austin last week, spurring considerable consternation from lakeside businesses and residents. LCRA general manager Becky Motal said Friday: “In a severe drought, there’s no guarantee for anybody on the lakes. It’s all a matter of rain and inflows.”
By lowering Lake Austin, the LCRA leaves room for it to capture between 4,500 and 7,000 acre-feet of water in a major rainstorm. The prime example of how this could work is September 2010’s Tropical Storm Hermine: The storm dumped about a foot of rain in Austin but considerably less over lakes Travis and Buchanan, just off the storm’s track. The heavy rains forced the river authority to open the floodgates at Tom Miller Dam, letting rainwater flow downstream.
“By not filling Lake Austin from Lake Travis, we might be able to catch a rain storm here,” Motal said. “We’ve seen in the past couple months that sometimes it’s raining on Lake Austin and not on Lake Travis.”
It’s also a water accounting gimmick of sorts: As long as lakes Travis and Buchanan hold above 600,000 acre-feet, the LCRA won’t have to impose mandatory water cutbacks.
Motal said she is not expecting board members to vote on such a move in their Sept. 17 and 18 meetings. Staffers are still weighing the idea.
What is the drought of record?
The LCRA uses three measures to indicate that a drought is worse than the 1950s drought of record. Ultimately, the river authority’s board must approve such a declaration, which still needs to be backed up by significant checking of calculations and measurements, but soon after the three conditions are met, mandatory cutbacks in water use kick in. Customers, like the city of Austin, the LCRA’s single largest, must then cut back their water use by up to 20 percent.
1. The lakes must have been below full for at least two years. This has been met.
2. The amount of water flowing into the lakes must be less than it was during the drought of record for six months. This has been met.
3. Lakes Travis and Buchanan must hold less than 600,000 acre-feet of water. (The record-low storage is actually 621,221 acre-feet.) This has not been met.