Weed Control Limited at Lake Webster
Public concern over chemical treatment of nuisance weeds in Lake Webster is prompting the Department of Natural Resources to limit the amount of herbicides used this summer at the 774-acre lake in Kosciusko County.
Last year anglers blamed a lake-wide treatment of Eurasian water milfoil, a non-native aquatic plant, for a decline in water clarity, development of algae mats, and disappearance of native plants that provide habitat for fish.
Local property owners hired a private company to apply fluridone to control the milfoil. Fluridone is approved by the U. S. Environmental Protection Agency and was used previously at Lake Webster in 1999 and 2002.
Based on information provided by the lake association to the DNR last May, milfoil covered half of the surface area where the water was less than 20 feet deep and threatened to interfere with boating.
The company hired to treat the weeds reported milfoil was controlled in the main area of the lake but additional treatments were needed in the Backwater Area, a wetland at the south end of the lake.
Anglers, however, complained that the treatment was excessive and exacerbated an already overly-aggressive weed control program.
"They killed just about every weed in the lake and fishing has gotten worse, especially for bass and muskies," wrote one disgruntled angler in an email message to the DNR.
Based on sampling by DNR biologists last August, milfoil had declined to no detectable level in the main lake but some native plants were also affected.
Although coontail, the most common native plant, was still present in many areas, its density was low. Coontail plants also showed signs of stress caused by the fluridone and were white in color (chlorosis). Sago pondweed and water stargrass were still present but at low densities.
Biologists, however, also reported seeing clumps of floating and dead algae throughout the lake.
Meanwhile, water clarity declined to only 2.5 feet, the lowest level since 2004 and down from a peak of 9 feet in 2008, and 5 feet in 2009.
Although DNR officials have approved a weed-control permit this year to allow spot treatment of milfoil, control of native plants is being limited.
Residents will only be allowed to treat native plants where significant nuisance stands are obvious and interfere with lake access.