The Highland Lakes are almost full again. Now what?

EDITOR’S NOTE: The following column is by LCRA Executive Vice President of Water John Hofmann and was submitted to area media organizations. DailyTrib.com is running it in full with only minor editing.

On July 2, our region was in a serious, years-long drought.

Then came July 3 and the start of heavy rains that caused devastating flooding throughout the Hill Country. By the end of the month, our water supply reservoirs were back to almost-full levels.

Welcome to Flash Flood Alley. It’s droughts and floods, and floods and droughts, and then more droughts, and then—you guessed it—another flood.

So what happens now that lakes Buchanan and Travis are close to full?  

The answer is anything.

We could go back to prolonged dry conditions, but it also wouldn’t take much rain for us to again have to open floodgates along the Highland Lakes. Remember: droughts and floods and floods and droughts. With that in mind, I wanted to offer a short primer for newcomers and maybe some old-timers who might be a little rusty on life with almost-full lakes.

First, the time to plan for floods is now. Not next month. Not next year. Now.

We don’t know what the rest of the year holds, and with rain in the right places, we could see flood operations needed quickly at every dam along the Highland Lakes.

Let me set the stage regarding the Highland Lakes, a chain of lakes northwest of Austin. From north to south, they are Lake Buchanan, Inks Lake, Lake LBJ, Lake Marble Falls, Lake Travis, and Lake Austin. 

The two largest lakes—Buchanan and Travis—are water supply reservoirs that are designed to fluctuate. The other lakes are known as “pass-through” lakes, built mainly for hydroelectric generation. The pass-through lakes are normally managed within a range of about a foot, but during a flood, flows are much swifter and water levels can be significantly higher.

Lake Buchanan is basically full. That means there is no room to store additional water, so any rain over the lake, or importantly, any rain upstream of the lake, will need to be passed downstream through Buchanan Dam through Inks Lake, Lake LBJ, and Lake Marble Falls into Lake Travis, the only one of the Highland Lakes designed to store floodwaters.

And did I mention Lake Travis is just a few feet short of being full?

If Lake Travis rises several more feet, the LCRA might need to open floodgates at Mansfield Dam for the first time since 2019 to send floodwater down the Colorado River through Austin and then Bastrop, Fayette, Colorado, Wharton, and Matagorda counties into Matagorda Bay. If the lower river is already running high, we might need to temporarily store water in the Lake Travis flood pool. (Stay with me here, because this gets a little complicated. Lake Travis is considered “full” at 681 feet above mean sea level (feet msl), but it has a large flood pool above 681 feet msl that can hold an additional 776,000 acre-feet of water, or the equivalent of 31 Lake Austins.)

That means people on the Highland Lakes and the lower river need to be ready. Know your flood risk. Develop your plan now.

To be blunt: If you are in an area where you could be affected by floodwaters on the Highland Lakes or Colorado River, you need to pay attention in a way you probably haven’t had to over the past few years. With lakes at these levels, you need to be on alert not just when it rains in your neighborhood but also when it rains upstream in the lower Colorado River basin, because that water will sooner or later flow into the Highland Lakes.

Things changed after the July rains, and our region is now in an entirely different operational posture than we were on July 2. Additional flooding could come quickly. We encourage Central Texans to join us in being prepared and ready to act if and when the time comes.

This is not a drill.

John Hofmann is executive vice president of Water for the Lower Colorado River Authority. For more information on flood preparedness along the Highland Lakes, visit www.lcra.org/floodmanagement.