EAU CLAIRE - A drawdown of the Chippewa Flowage last fall should benefit local residents, property owners and other users of the Chippewa Flowage, according to a partners group that assists in management activities of the reservoir and surrounding lands to benefit the area's ecosystem.
The goal of the project is to reduce aquatic plants like the invasive Eurasian water-milfoil, which has grown to nuisance levels in some areas of the flowage, according to Max Wolter, Department of Natural Resources fisheries biologist. Wolter said biologists also expect changes in the aquatic habitat will benefit the walleye and musky fishery by improving their spawning habitat.
The late fall and early winter drawdown on the 15,300-acre reservoir, which has a current elevation of about 1,310 feet above sea level, slowly brought the water level down 8 feet. The main difference between this year's drawdown and previous years is that 5 feet was drawn down before ice-up. This is expected to minimize issues with low oxygen levels that can arise during later winter draw downs.
Wolter said the drawdown is intended to expose the bottom sediment to air as winter progresses, freezing out the roots of the Eurasian water-milfoil. During spring runoff, water levels will be restored to normal elevations. Precipitation and inflow from tributary rivers and streams will determine how quickly this happens. The reservoir is full at 1,313 feet.
"Drawdowns are frequently used to manage fish populations across the United States," Wolter said. "Significant drawdowns were a big part of the history of the Chippewa Flowage up until the mid-1990s, and during that period of time walleye recruitment was high. The current plan is conservative enough to allow access for fall and winter fishing, yet still have a beneficial impact on the select resources."
Throughout the 2013-2014 project, the group has been monitoring key areas for winter dissolved oxygen levels.
As the group expected -- based on the extended and harsh winter -- they have observed low dissolved oxygen levels in a few isolated areas, specifically Crane Lake and Blueberry Flats. These areas represent less than 3 percent of the flowage's acreage.
"While we won't know for sure about fish kills until after the ice melts, so far the main lake area look good, or even better than expected," Wolter said. After ice-out biologists will monitor the response of the aquatic plant and fish populations.
The Chippewa Flowage Partners Group -- which comprised of Xcel Energy, Department of Natural Resources, U.S. Forest Service, Chippewa Flowage Area Property Owners Association, Lake Chippewa Flowage Resort Association, Lac Courte Oreilles (LCO) Band of Lake Superior Chippewa Indians, Wisconsin Conservation Congress (Sawyer County) -- has been in existence since 2006 to assist in management activities of the reservoir and surrounding lands to benefit the whole ecosystem of the Chippewa Flowage.