On Nov. 15, 2012, the City of Eden Prairie completed a treatment of aluminum sulfate (alum) to Round Lake.

The reason for the alum treatment was to reduce the impact of phosphorus in the lake. Phosphorus is inactivated by alum, thus decreasing total phosphorus in the water. Less phosphorus means less algae growth. Alum is safe from a human, animal and environmental standpoint, and has historically been used to treat excessive phosphorus levels in many lakes.

Since 1972, the City of Eden Prairie has tracked phosphorus as part of its efforts to monitor water quality. Phosphorus loads have increased as the community has developed and the City is actively looking at ways to improve water quality through techniques such as alum treatment.

There are many ways residents can help to improve water quality by reducing external nutrient loads that enter the stormwater sewers, including:

• Eliminate or reduce fertilizer application
• Bag grass clippings before they wash down the storm sewer
• Sweep clippings back into grass after mowing in lieu of fertilizing your yard
• Rake up leaves before it rains during the fall season