The Highland Lakes were created to manage floods and capture water when it rains to ensure the region has a reliable water supply during dry times. Lakes Buchanan and Travis – the region's water supply reservoirs – provide water for more than a million users, including communities, industries, businesses, agriculture and the environment in the lower Colorado River basin. Together, lakes Buchanan and Travis can hold about 2 million acre-feet of water. It's important to note that none of the Highland Lakes are constant-level lakes.
Inflows and lake level projections
Heavy rains in October brought historic flooding to the Highland Lakes. The lakes received more than 1.3 million acre-feet of inflows, the highest October inflow total in history.
At one point, flows into Lake Travis were 375,000 cubic feet per second - an amount of water that would fill the Astrodome in less than two minutes.
LCRA moved floodwater downstream through the Highland Lakes dams to Lake Travis, where it was stored in the flood pool until LCRA could release it in a controlled manner downstream, saving Austin and other downstream communities from catastrophic flooding.
As floodwater rose in the flood pool, Lake Travis reached an elevation of 704.39 feet above mean sea level, its fifth highest elevation in history.
At 1,323,094 acre-feet, inflows into the lakes in October were about 997 percent of the historic monthly average and were the fourth highest of any month on record. Inflows are the amount of water flowing into the lakes estimated from measurements at four gauges upstream. (An acre-foot is 325,851 gallons.)
Here are LCRA's six-month projections for Lake Travis and Lake Buchanan based on conditions ranging from very wet to very dry.