The Louisiana Department of Wildlife and Fisheries (LDWF), in collaboration with the Louisiana Department of Transportation and Development (DOTD) initiated a drawdown on Lake Bistineau on Wednesday, Sept. 16.
The purpose for the drawdown is to strand giant salvinia, a non-native, invasive floating plant in the lake and allow for the salvinia to dry out. While the lake is down, department biologists will conduct intensive ground and aerial surveys to determine where giant salvinia persists in areas that are left with standing water.
"The drawdown of Lake Bistineau marked a critical step in our department's efforts to restore use of this lake to property owners and visitors alike," said LDWF Secretary Robert Barham. "I have made the recovery of this lake one of the department's top priorities."
Lake Bistineau encompasses 17,200 acres and expands across Webster, Bossier and Bienville parishes. Giant salvinia was originally discovered in the lake in early 2006 and has steadily expanded its coverage each succeeding year.
To control its spread in 2008, LDWF conducted a summer drawdown beginning in mid-July and applied foliar herbicide treatments to reduce the coverage from 4,500 acres to approximately 850 acres. This year's drawdown commenced two months later than in 2008 and the giant salvinia re-growth had expanded to exceed 7,000 acres.
The rate at which the lake will be lowered will depend on rain events in the watershed, but is expected to be several inches per day. The water control structure now in place is capable of lowering the lake by seven feet. Historically, it takes five to six weeks to lower the lake at this rate. No date has been set at this time to close the gates.
In recent weeks, Mark McElroy, LDWF biologist program manager, and other department biologists have been investigating alternative methods to control giant salvinia in Lake Bistineau for the long term and the preliminary version of a new aquatic plant control plan is nearing completion. "There are many contributing factors for giant salvinia growth in Lake Bistineau and we'll be taking a different approach to control that growth," said McElroy.
The plan is expected to be a comprehensive approach to managing the plants and will require the implementation of multiple strategies, many of which require partners and additional funding.
