Lake levels continue slow rise even with below-average inflows
Welcome rain in April led to an 18,000 acre-foot increase in the combined storage of lakes Buchanan and Travis – LCRA’s reservoirs that store water supply for the region. However, inflows – or the amount of water feeding the Highland Lakes – remained below average and continued to indicate the Texas Hill Country has not recovered from the record-breaking drought that began in 2008. Inflow calculations are based on the amount of water flowing into the Highland Lakes from rivers and tributaries measured at four streamflow gauges.
April 2015 inflows were 22,726 acre-feet – about 22 percent of the April average – and were the 19th lowest inflows for the month on record.
The amount of water in lakes Buchanan and Travis increased to 767,094 acre-feet on May 1 – the third lowest amount of water in the lakes on that date since 1942, when Mansfield Dam was completed. (An acre-foot is 325,851 gallons.)
As of early May, lakes Buchanan and Travis stood at 38 percent of capacity.
“At the start of the year, the lakes were 34 percent full,” said John Hofmann, LCRA executive vice president of Water. “The amount of water stored in lakes Buchanan and Travis has risen nearly 78,000 acre-feet since January, which is a significant bump. It’s a good start, but the drought is a far cry from being over. Temperatures are beginning to heat up, and conservation will be critical as we move into the hottest months of the year.’’
Preliminary 2014 data shows this drought is now the most severe the region has experienced since construction of the dams that created the Highland Lakes began in the 1930s.
The severity of the drought has reduced the amount of water LCRA can provide reliably each year through a repeat of the driest conditions on record by 100,000 acre-feet, to 500,000 acre-feet. The revised inventory estimate reduces the amount of water LCRA will have available for sale in the future, but does not impact existing contracts.
Six of the 10 lowest annual inflows on record have occurred during this drought. Average annual inflows for 1942-2014 are 1,216,295 acre-feet.
- The lowest annual inflows occurred in 2011 with only 127,802 acre-feet, about 11 percent of the annual average.
- The second lowest inflows were 209,023 acre-feet – about 17 percent of the annual average – in 2014.
- The third lowest inflows were 215,138 acre-feet – about 18 percent of the annual average – in 2013.
- The fourth lowest inflows were 284,462 acre-feet – or about 23 percent of the annual average – in 2008.
- The seventh lowest inflows were 393,163 acre-feet – or about 32 percent of the annual average – in 2012.
- The 10th lowest inflows were 499,732 acre-feet – or about 41 percent of the annual average – in 2009.
Without additional rain in the Highland Lakes watershed, there is a small chance – less than 1 percent – the combined storage of lakes Buchanan and Travis could fall to 30 percent of capacity, or 600,000 acre-feet, in the July-August 2015 time frame. The chance of reaching 600,000 acre-feet in combined storage remains less than 4 percent through the end of 2015.
If combined storage falls to 600,000 acre-feet, the LCRA Board of Directors would issue a “Drought Worse Than Drought of Record” declaration under the 2010 Water Management Plan. At that point, LCRA would require cities, industries and other firm customers to reduce their water use by 20 percent from a baseline year, and LCRA also would cut off all Highland Lakes interruptible water.
Though lake levels are low, the Highland Lakes are doing exactly what they were designed to do. The lakes capture water when it rains to ensure the region has a reliable water supply during times of drought. Lakes Travis and Buchanan provide drinking water to more than a million people and water to industries, businesses, the environment and, when enough water is available, agriculture in the lower Colorado River basin.
In order to preserve the water supply, LCRA – with permission from the state – cut off Highland Lakes water to most interruptible water customers in 2012, 2013 and 2014. In March, the Texas Commission on Environmental Quality approved
emergency drought relief again through June 18.
LCRA also is increasing the water supply for the region by building the first new water supply reservoir in the lower Colorado River basin in decades. The
Lane City Reservoir is the first project that will allow LCRA to capture and store significant amounts of water downstream of the Highland Lakes. The reservoir could add up to 90,000 acre-feet per year to LCRA’s water inventory and is expected to be completed in 2017. The new reservoir will help reduce the amount of water that otherwise would be required to be released from the Highland Lakes.