Why did flood gates need to be open on the Highland Lakes despite the drought?

MARBLE FALLS, TX (KXAN) -- On Wednesday, September 4, thousands of gallons of water poured through the flood gates at Max Starcke and Wirtz Dams. It was the second time in six weeks the dams had to open their gates.

While this summer has been dry, flood gates having to be open during this time period isn't unusual, according to the LCRA.

"Because Lake LBJ is a hydroelectric (dam) and a source of cooling water for a power plant, it has no flood control storage or water supply storage, and so whatever comes into that reservoir has to go out that reservoir. There's no excess storage for it," said John Hofmann, Executive Vice President of Water for the Lower Colorado River Authority.

Lake LBJ and Lake Marble Falls, where the two dams are located, are both designed for this purpose: to provide a power source for the two hydroelectric dams.

"Because they maintain a pretty stable operating level, it doesn't take very much water coming into that system to require you to have to pass those flows. We generally do that with hydroelectric operations, and when we get more flow coming in than what our hydro operations can pass, then we have to look at opening gates," Hofmann said.

Water storage on the Highland Lakes

The Highland Lakes are dominated by two major reservoirs, Lake Buchanan and Lake Travis. These two lakes hold the majority of the drinking water for people living in Austin.

Between these two lakes are smaller "pass-through" lakes. These include Inks Lake, Lake LBJ, Lake Marble Falls, Lake Austin and Lady Bird Lake. Dividing these lakes are several hydroelectric dams.

Most of the power these dams generate is used to keep moving water through the Highland Lakes. The power isn't actually fed back into the grid unless there is a state-wide emergency, like the 2021 Winter Storm.

"A reservoir is stored power. If you think about what a hydroelectric operation is, the water that it moves through the system is basically the storage of that power. And it's not until you turn the hydro operation on that, that power is released through the generators," Hofmann said.

This means the reservoirs are not only storage for water, but essentially a giant battery waiting to be used.

Will the gates open again anytime soon?

Rain chances are very low in the coming days, according to the First Warning Weather Team. Also, La Niña is returning to the forecast.

La Niña, a climate system originating in the Pacific Ocean, typically means a warm, dry winter. So expect less rain in the forecast in the coming months.

"We're going to need to continue to talk in Central Texas about how we use our water, and to think about using water differently than maybe what we have in the past. And I think that conservation ethic is going to be really, really important for us to stress regardless," Hofmann said.