Minnesota’s Fish Lake, a 232-acre lake bordered by a regional park with a swimming beach and public water access, achieved the phosphorus reductions necessary to be considered for delisting in 2017, after the first dose of a two-part alum treatment.
Alum treatments are applied in two half-doses to avoid a significant drop in pH, which could harm fish and invertebrates. Half-dose treatments also improve the efficiency of alum to bind to the phosphorus, locking it up within the upper layer of sediment.
