Copper sulfate is toxic to other plants and fish and can be detected as a residue within plants and fish. A level of 1 part per million is usually considered the upper level of treatment. This is equivalent to 8 pounds of copper sulfate per 1,000,000 gallons of water. The copper sulfate must be spread evenly across the water surface. Placing the copper sulfate crystals in a burlap bag and towing behind a small boat until the crystals are dissolved is one method.
Treatment is most effective if applied just as the bloom is forming.
One treatment is usually satisfactory for two to three weeks. V-1136, August 1997 NDSU Extension Service, North Dakota State University of Agriculture and Applied Science, and U.S. Department of Agriculture cooperating. Sharon D. Anderson, Director, Fargo, North Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914.