Due to dry weather and the low inflow, the Highland Lakes’ firm yield, which is an inventory of water LCRA can provide reliably every year, has been decreased by about 100,000 acre-feet, to 500,000 acre-feet per year. And the firm yield could continue to drop, according to LCRA data. An acre-foot of water is 325,851 gallons.
Six of the 10 lowest inflow years have all happened since 2008.
“We’re in a historic drought like we’ve never seen in our lifetimes,’’ LCRA General Manager Phil Wilson said in a prepared statement. “Even in these conditions, however, lakes Travis and Buchanan remain significantly above their all-time lows, thanks to smart water management decisions and excellent water saving efforts by our customers throughout the lower Colorado River basin.”
The LCRA manages the Highland Lakes and lower Colorado River. The river authority also generates power for the region and operates area parks, among other responsibilities.
On Wednesday, the lakes contained about 717,000 acre-feet, or 36 percent of capacity. That’s nearly 100,000 acre-feet more than the 1952 all-time low combined storage of 621,221 acre-feet, or 32 percent of capacity. The revised estimate of the firm yield changes the amount of water available for sale in the future, but does not impact existing contracts, such as those held by the City of Austin and other firm customers, according to the LCRA.
“LCRA has water available to meet all our existing contracts,” Wilson said in a prepared statement. “The good news is the reservoirs are doing what they were designed to do – capturing water when it rains, and holding it for use during droughts.”
LCRA will work on expanding its water supply further, Wilson said, including the construction of a new reservoir near the coast. LCRA began building the Lane City Reservoir in Wharton County in late 2014. The reservior is expected to hold 90,000 acre-feet of water and be completed in 2017.
The firm yield is unrelated to trigger levels in the 2010 Water Management Plan that determines how water is divvied up among customers during drought. The plan sets out three triggers that must be met before the LCRA Board issues a Drought Worse Than Drought of Record declaration. Those triggers are:
- 24 months since lakes Travis and Buchanan were full.
- Prolonged low inflows worse than inflows during the 1947-57 drought.
- Combined storage in lakes Travis and Buchanan at less than 600,000 acre-feet.
If the LCRA declares the current drought to be worse than the drought of record, it would cut off Highland Lakes water for certain customers and impose water-use cutbacks of 20 percent for firm customers. Current estimates show combined storage could potentially hit 600,000 acre-feet in May or June.