As of June 7, Lake Buchanan is 94 percent full with a height of 1017.7 feet mean sea level (msl).

"Lake Buchanan is considered full for water supply purposes at 1020 feet msl," said Clara Tuma, the Supervisor of External Communications/Public Information Officer for the Lower Colorado River Authority (LCRA).

So why is the LCRA releasing water through Buchanan Dam, when Lake Buchanan isn't even full? The answer primarily has to do with the difference between Lake Buchanan and Lake Travis.

Lake Travis is the only Highland Lake that has what's called a "flood pool." When Lake Travis is 100 percent full, there is still 33 feet to the top of the spillway at Mansfield Dam.  Lake Buchanan does not have a flood pool, so when it's at 100 percent capacity, it's completely full.  Lake Travis on the other hand may be 121 percent full, but it's still over 21 feet from the spillway. 

"A 1990 agreement with FEMA requires LCRA to manage the lake at or below 1,018 feet msl during the flood-prone months of May through October, and 1,020 feet msl the rest of the year," said Tuma.

This allows the LCRA to control Lake Buchanan in a flash flood situation, just as the the flood pool does at Lake Travis.

But don't expect Lake Buchanan to be able to reach 100 percent capacity anytime soon, even outside of the rainy season.

"In addition, LCRA is in the midst of a multiyear project to upgrade Buchanan Dam.  During that project, we are managing the lake to at or below 1,018 feet msl year-round.  So, we are managing the lake to 1,018 feet msl because of both the FEMA agreement and the construction project," explained Tuma.