Surveys on Bald Eagle Lake have been completed and, surprisingly enough, Eurasian watermilfoil weed treatment was not needed this summer.
Matt Kocien of the Rice Creek Watershed District (RCWD) and Steve McComas of Blue Water Science recently conducted a plant survey of Bald Eagle Lake. They determined that treatments for curly-leaf pondweed, conducted over several years, have been highly successful. Curly-leaf was treated again in April with great results, as shown in the accompanying mapping survey. There was some light growth but overall the reduction in curly-leaf pondweed has been very effective.
The survey found light, scattered growth of Eurasian watermilfoil. About 42 acres were treated in 2018, mostly at the south end of the lake. This summer, they found no re-growth, so there was no need for treatment.
A midsummer survey will be conducted to check again for non-native milfoil growth and to check on other native aquatic plants and their growth status. White-stem pondweed is quite prolific this summer on Bald Eagle but is a native plant. It’s easier to navigate through because its leaves are flat and loosely structured, unlike Eurasian watermilfoil, which has a tendency to wrap around boat propellers.
Curly-leaf pondweed and Eurasian watermilfoil became quite a nuisance for boat navigation and overall lake enjoyment. This enhanced weed growth was not surprising to the governmental agencies involved in the alum treatment in spring of 2014 and 2016. It was predicted that weed growth would increase along with water clarity. In 2016 and 2017, the DNR defined the lake’s Eurasian watermilfoil to be at a nuisance level, which means it significantly impaired boat navigability. Both curly-leaf pondweed and Eurasian milfoil have been treated over the last several years and, as it was predicted, the lake has taken on most of the management of its weed growth on its own following three years of alum treatments.
The aluminum sulfate (alum) treatment resulted in a 67% decrease in phosphorus and a 69% decrease in algae growth while water clarity improved by 63%. This resulted in enhanced water clarity (more than 5 feet) and advanced vegetation growth. From 2001-2008, readings for water clarity (Secci disk readings as reported to the MN PCA) showed visibility down only 5 feet and often less in late summer. After the initial alum treatment in 2014, water clarity improved to 11 feet at the maximum, and after the second alum treatment in 2016, the maximum reading moved up to 16 feet.
The alum treatments were a result of funding and the collaboration of several agencies, including the Rice Creek Watershed District, the Board of Water and Soil Resources’ Clean Water Fund, the Minnesota Pollution Control Agency and the Bald Eagle Lake Water Management District.
Partners in the restoration also included the city of Hugo, lakeshore property owners and Oneka Golf Course. The three-pronged approach included alum treatments, the golf course water retention program and lakeshore owners who actively remediated shorelines to reduce stormwater runoff. This joint project was so successful that the Rice Creek Watershed District was given national recognition from the North American Lake Management Society. In 2017, Bald Eagle Lake water quality was restored and met the state standards for nutrients, algae and clarity for the first time since 1980.
Of some recent concern to Bald Eagle Lake water quality is the overflow from White Bear Lake and the possibility of migrating zebra mussels. White Bear Lake is now at one of its highest water levels in years, resulting in an outflow from the north end through Ditch 11, which flows into Bald Eagle Lake and the Rice Creek watershed. Both Steve McComas of Blue Water Science and Keegan Lund of the DNR believe it is unlikely that any invasive species would survive a transfer from White Bear Lake through Ditch 11 to Bald Eagle Lake. It continues to be more likely that transfers of zebra mussels would be from boats, trailers or float planes.
It’s because of the coordination and cooperation between multiple government agencies that Bald Eagle Lake’s water quality restoration efforts have been measurably successful. The Bald Eagle Area Association will continue to work towards maintaining and enhancing the lake for the enjoyment of the community.
Contacts to call for comments: Bart Crockett, president BEAA 651-334-5110; Steve McComas, Blue Water Science, 651-690-9602; Matt Kocien, Rice Creek Watershed District, 763-398—3075.