L.D.W.F. TAKES STEPS TO CONTROL NANTACHIE LAKE AQUATIC VEGETATION

Release Date: 07/04/2006

The Louisiana Department of Wildlife and Fisheries (LDWF) has proposed a drawdown for Nantachie Lake in Grant Parish beginning July 17, 2006 and ending January 31, 2007.  This will be the second of three drawdowns recommended in an aquatic plant management plan submitted by LDWF in August of 2005.  The Grant Parish Police Jury agreed to the drawdown at a meeting on June 27, 2006.  


The drawdowns were prompted by numerous calls concerning submergent aquatic vegetation (SAV) received by fisheries personnel in the LDWF District 3 office.  In addition to native SAV, hydrilla, an exotic noxious aquatic weed, has become established in the lake and is hindering boating access and recreational opportunities in many areas of the lake.  Hydrilla was first located at the public launch on the southeast end of the lake and has spread throughout most of the southern half of the lake.


The July 17 start date is necessary due to the slower than normal ability to dewater the lake.  During the 2005/2006 drawdown it was determined that the lake could only be lowered approximately 2 inches per day.  Dewatering at a faster rate could cause flooding of downstream property.  The lake will be drawn down approximately 7 feet below pool stage.


Hydrilla requires water to survive; therefore, removing the water causes the plants to die.  This is more economically feasible than using expensive herbicides.  When possible, multi-year drawdowns are preferable to reduce the numbers of reproductive structures (tubers) deposited in the bottom substrate by hydrilla. Drying the water bottom stimulates the majority of tubers to sprout.  This reduces the amount of existing tubers in the hydrosoil the next year.  The drawdowns are also timed to prevent the production of tubers in the fall.  The first drawdown must be followed by other drawdowns in following years to prevent the existing plants from setting more tubers and to stimulate the remaining tubers to sprout in each year of the project.  With the combined reduction of the tuber bank from each drawdown, tubers available for re-infestation will be significantly depleted.  Additionally, having the drawdown last until January 31 could expose the plants to frosts and freezing weather which would increase the reduction of plants.


For additional information, please contact Ricky Moses at 318-487-5888 or email at rmoses@wlf.louisiana.gov.


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