Over the last few days, the entire lower Colorado River basin from well above Lake Buchanan to Matagorda Bay has received a great deal of rain. The rain in the Highland Lakes watershed has been more than lakes Buchanan and Travis can safely hold without allowing levels to rise significantly higher in the flood pool on Lake Travis.
Assuming there is no additional rainfall over the weekend, LCRA anticipates more than 70,000 acre-feet of water will flow into Lake Buchanan over the next three to four days. To safely and gradually move this additional water downstream through the Highland Lakes, LCRA has planned and will take the following steps over the next few days:
Buchanan Dam (which creates Lake Buchanan): Hydroelectric generation and floodgate operations will continue. This will allow Lake Buchanan to remain at or near a maximum storage level of approximately 1,018 feet above mean sea level.
Wirtz Dam (which creates Lake LBJ) and Starcke Dam (which forms Lake Marble Falls): Floodgate operations and hydroelectric generation at Wirtz and Starke dams will continue.
Mansfield Dam (which creates Lake Travis): The hydroelectric generation that began Thursday will continue. Additionally, on Monday LCRA will open a floodgate at Mansfield Dam about 8 a.m. This will allow water to flow downstream from Lake Travis at a rate that can be safely passed through Austin and downstream communities. LCRA anticipates the gate will remain open for at least 48 hours.
Tom Miller Dam (which creates Lake Austin): Hydroelectric generation and floodgate operations will continue.
Additionally on Monday morning, LCRA will increase the floodgate flow at Tom Miller Dam to accommodate the increased flow entering Lake Austin upstream from Mansfield Dam.
Waiting until Monday morning to begin floodgate operations at Mansfield Dam will allow floodwaters in the river below Austin to further subside in the lower basin.
Discharges from the Highland Lakes will reach the lower basin in five to seven days, and will not contribute to current flooding in the area.