State weed control for Sylvan Lake ends this year


State weed control for Sylvan Lake ends this year

The third in a three-year series of state-funded herbicide applications to control curly-leaf pondweed in Sylvan Lake is set for later this month.

Plans are to apply a low-dose concentration of Aquathol K® to 270 acres of water in the 669-acre lake when water temperatures approach 50 F.

Aquathol K® is approved for use in public waters by the Environmental Protection Agency and the Office of the Indiana State Chemist.

Curly-leaf pondweed is an aquatic weed not native to Indiana lakes. It develops quickly in the spring as temperatures rise and can shade out beneficial native plants.

By applying the herbicide early, any potential harmful effects on native plants, which typically begin to grow later in spring, are minimized.

Funds to cover cost of the herbicide application come mostly from the Lake and River Enhancement (LARE) Program administered by the DNR Division of Fish and Wildlife (DFW). The money is generated from a fee charged to boat owners.

This year's treatment is expected to cost more than $50,000 and includes additional funds to control Eurasian water milfoil, another invasive, non-native plant found in the lake.

Although the DFW will pay a portion of the cost, the Sylvan Lake Improvement Association will cover the remaining share.

For decades, curly-leaf pondweed grew throughout Sylvan Lake and created nuisance conditions around boat docks and swimming beaches. It also blanketed much of the shallow water areas in undeveloped areas around Boy Scout Island and in Pit Basin, and made fishing difficult.

Until 2007, Sylvan Lake residents bore the full cost of treating curly-leaf pondweed but limited their treatments to residential sections of shoreline.

Untreated areas, however, served as a source for re-infestation of treated areas each year.

In 2007, the association received a LARE grant and permit from the DFW to conduct a three-year, lake-wide curly-leaf pondweed control program in hopes of reducing it to a manageable level.

The initial treatment reduced curly-leaf pondweed abundance by 74 percent. However, curly-leaf pondweed produces seed-like structures called "turions" that can remain viable for several years.

"Follow-up treatments in 2008 and 2009 are necessary to kill new plants that sprout from the turions," said Angela Sturdevant, a LARE aquatic biologist who oversees the control program at Sylvan Lake. "By 2010, we think only spot treatments of curly-leaf pondweed in areas where it re-appears should be needed."

Marty Benson, assistant director of communications, (317) 233-3853; cell (317) 696-9812

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