In terms of effectiveness, the wetland settling ponds installed at Lake Calhoun have prevented the growth of an estimated 180,000 pounds of algae by removing phosphorous. An estimated 30,000 pounds of suspended sediments were also removed. Lake Calhoun was recently given an A grade in water clarity and water quality. The Lake Nokomis ponds will be landscaped with prairie and wetland plants, which will benefit from the phosphorous. The ponds design will be integrated into existing park land, enhancing the natural beauty of the park.
Grit chambers are below-ground chambers that are part of the storm water drainage system.
Two will be installed at Woodland Avenue and 50th Street and 53rd Street and Shoreview Avenue. At Lake Nokomis, a new type of grit chamber design will be used. The principle of gravity is used to design a circular prefabricated concrete holding tank that allows the grit and debris to sink to the bottom, keeping it from entering the lake. A number of actions are planned to work together in cleaning up the lakes, including carp removal later this winter from Lake Nokomis. Carp tend to stir up lake bottoms where the phosphorous has settled, hurting water quality and creating algae bloom.