Report Investigates Wisconsin Lake's Pollution

The amount of pollutants entering Lake Mallalieu from the storm water drainage system in Hudson, Wisc., must be reduced, according to a recently completed study. Researchers recommend that the city of Hudson improve its storm water system and encourage behavioral changes to prevent pollution in the first place.

Bonestroo, the city's consulting engineering firm, submitted a 22-page draft report on its Lake Mallalieu Storm Water Assessment Nov. 16. At the encouragement of the Lake Mallalieu Assn.--an organization of lakeside homeowners--the city of Hudson ordered the study and Bonestroo conducted the assessment. The Wisconsin Department of Natural Resources (DNR) helped fund the lake study.

Phosphorus is of great concern to the study's leaders and Hudson residents. A computer model run by Bonestroo determined that 177 lb of phosphorus enters Lake Mallalieu annually. The lake, a 270-acre reservoir on the WIlliow River, is on Wisconsin's list of impaired waters due to its phosphorus levels. Major upstream sections of the WIllow River are also listed for this reason.

Another problem Bonestroo pointed out in its report is the approximately 54,800 lb of suspended solids being carried into the lake each year by city storm sewers. Bonestroo's report recommended Hudson city officials call for the construction of one or two treatment ponds near where runoff enters Lake Mallalieu.

The firm also suggested the installation of five underground hydrodynamic separators; the construction of rain gardens or infiltration trenches from short sections of streets and parking lots; the placement of rain barrels to catch and hold rooftop runoff; the redirection of downspouts to carry rooftop runoff to more permeable areas; more frequent street sweeping; and an increased emphasis on public education.

"Everyone in the project area is a lakeshore resident with regard to their ability to help or hurt the lake," the report stated.

The state DNR offers a number of grant programs that could help fund some of the initiatives outlined in the report. Hudson city officials are currently reviewing the aforementioned proposals.

Source: Hudson Star-Observer