Posted: Wed, 5 Jan 2011 03:15 PM - 15,762 Readers

By: Erin Cargile

The Lower Colorado River Authority is lowering Lake Austin 12 feet to allow the city to fight a variety of unwanted plants. They include Eurasian water milfoil, which grows near the shore with feathery foliage, duckweed , a small flowering plant, and hydrilla , a waterweed that grows in deeper water.

Last year, the lake could not be lowered due to drought conditions.   Steve Magnelia, a biologist with Texas Parks and Wildlife Department, said that is part of the reason why 37-percent of Lake Austin is covered with the vegetation. Those are the results of a survey conducted in November 2010. Tests are run every couple of months.

Hydrilla -- an aggressive, non-native aquatic plant -- was first discovered in the lake in 1999 and poses a threat to boaters and swimmers. Hydrilla can grow all the way up to the surface and get caught in boat propellers and entangle swimmers. The City of Austin has added thousands of sterile grass carp to control the hydrilla in the past. TPWD has recommended doing it again.

Biologists say milfoil is the most problematic. For right now, the city will try to dehydrate the plant by exposing the leaves and roots to the air.

LCRA started the slow drawdown Jan. 3 which will be complete Jan. 24. Significant rain could slow down the process. During the three-week period, Lake Austin 's water level will fall about half a foot per day. During this time, lakeside homeowners are also encouragd to build and maintain docks.

Lake levels should be restored by Valentine's Day, according to officials.

LCRA has lowered Lake Austin at the city's request since the 1950s. It helps control vegetation by exposing the plants to the air and killing off the leaves and stems by dehydration, providing temporary relief, particularly in the shallow areas where the plants are exposed.