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
Runoff into the Highland Lakes from the heavy rains in October continued into November. At 115,420 acre-feet, inflows into the lakes in November were about 165 percent of the historic monthly average.
November inflows were the second-highest monthly inflows to the Highland Lakes for 2018, second only to the 1.3 million acre-feet of inflows received during historic flooding in October. The October inflows were the highest October inflows in history and 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.