A small portion of the Ann and Roy Butler Hike and Bike Trail will be closed to both foot and bike traffic while Austin Energy performs maintenance on the Longhorn Dam. The work started Monday, Aug. 18, and is expected to last until Monday, Sept. 15. Trail closure will be Mondays through Fridays from 7 a.m. to 5 p.m.



To minimize the impact on trail users, a southbound lane of Pleasant Valley Road will be blocked from vehicular traffic and made available to walkers and bikers while the maintenance is underway. This barricade will be up for the duration of the work, even when the trail is open.



Two lanes of Pleasant Valley Road also will be intermittently closed to allow space for a crane. During these times, bicycle and pedestrian traffic from the trail will be guided back and forth from one side of the dam to the other.



The closures are to ensure the safety of the public and workers. Traffic control will be displayed to help direct motorists and pedestrians. Motorists are asked to use caution and be extra alert in the work zone during this time.



Longhorn Dam was completed in 1960 with the purpose of creating a cooling lake for the Holly Street Power Plant as well as the Seaholm Power Plant. The two automatically controlled bascule gates, along with the six manual floodgates, help the city keep a standard level for Lady Bird Lake. The bascule gates work on a float system. When the water level rises above a certain point, the gates open and close when the float is lowered back to an acceptable level. These systems also are critical in managing flood levels during a flood event.



Repairs to the dam are needed to ensure that it functions efficiently while maintaining a clean lake environment. The maintenance will service the hydraulic system involved in the dam’s bascule gates. Workers will reconstruct several hydraulic pumps to ensure they are functioning properly and sealed correctly as well as other maintenance. The hydraulic fluid in the pumps will be replaced with environmentally friendly fluid that meets equipment requirements.



The last time this type of work was performed on the dam was in 1993. ###