LCRA has revised its forecast and now projects that Lake Travis will peak at 687 to 688 feet above mean sea level (msl) tonight or possibly early Monday.
Based on rainfall that has already fallen, floodgate operations are not planned at Mansfield Dam, which creates Lake Travis. Lake Travis is in its flood pool with a 6 a.m. elevation at 686.6 feet msl; the lake is considered full at 681 feel msl. LCRA projects the lake will continue to rise before cresting between 687 to 688 msl feet msl Sunday, or possibly early Monday. These projections could change with additional rain.
To pass the floodwaters from Lake Travis, LCRA is operating hydroelectric-generating units at Mansfield Dam to release about 5,000 cubic feet per second. Downstream of Lake Travis, a floodgate at Tom Miller Dam in Austin is partially opened and hydroelectric-generating units are operating to safely release floodwaters downstream.
Floodgate open at Starcke Dam
Upstream of Lake Travis, LCRA has closed a floodgate opened Friday at Wirtz Dam, which creates Lake LBJ, but a floodgate at Starcke Dam, which forms Lake Marble Falls, remains partially open. This floodwater funnels into Lake Travis — the only flood control reservoir on the Highland Lakes system.
Floodgate operations are not planned at the northern-most dam along the Highland Lakes chain, Buchanan Dam. However, these operational plans may change quickly with additional rainfall or changes in conditions.
Possible impact from Hurricane Dean
LCRA is monitoring Hurricane Dean, which is tracking to hit the northern coast of Mexico, south of Brownsville, and could bring more rain to the region by the mid-to-late next week. Depending on currents and weather conditions, water released from Lake Travis takes about a week to reach the coast; thus, by containing floodwaters Lake Travis is holding water that could otherwise add to flooding problems downstream if the hurricane affects the Colorado River basin.
Operating rules restrict opening floodgates
Lake Travis, which was specifically built to contain floodwaters until they can be safely released downstream, is operated based on rules from the U.S. Army Corps of Engineers that consider both forecasted Lake Travis levels and river levels at locations downstream of Austin. The operating rules limit LCRA from stepping up water releases — for example, by opening one or more of the dam's 24 floodgates — until the lake is forecast to reach 691 feet msl.
Boaters: Avoid creating wakes near low-lying structuresWhile Lake Travis remains open to recreational boating, LCRA staff has installed no-wake buoys along a one-mile stretch of the lake near Graveyard Point, the subdivision that is the first to be affected when Lake Travis is in its flood pool. At the level Lake Travis is forecast to reach this weekend, homes in the lowest areas could be damaged by wakes created by boats.
Moreover, LCRA advises boaters to exercise extreme caution. LCRA personnel have reported seeing heavy debris along the Pedernales River that may eventually flow into Lake Travis and make boating hazardous at or near the confluence with the Pedernales River.
LCRA also reminds people of the hazards associated with boating or swimming in water that has received runoff from heavy rains. While swimming in lakes and rivers always carries a risk of illness caused by bacteria, swimming in natural water bodies immediately after flood events increases this risk. Higher bacteria levels typically return to normal in about a week to 10 days after the peak runoff.
MORE: Situation Report
