In 2003, Wisconsin poisoned every fish in a degraded lake, then sealed its bottom with alum: Phosphorus fell 85% and algae dropped 90%

In 2003, managers who were restoring Silver Lake in Manitowoc County, Wisconsin used rotenone to eradicate the lake's existing fish community, which was dominated by rough fish such as carp and bullheads. The operation was part of a larger attempt to rescue a 69-acre lake that had suffered decades of heavy phosphorus pollution, persistent algal blooms and occasional fish kills.

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