Water quality and the effects of changes in phosphorus loading, Red Cedar Lakes, Barron and Washburn Counties, Wisconsin

The Red Cedar Lakes consist of three mainstem lakes (Balsam, Hemlock and Red Cedar) on the Red Cedar River in Barron and Washburn Counties, Wisconsin. These lakes are productive because of high phosphorus loading, and classified as mesotrophic to eutrophic. Because of concerns that the water quality of these lakes was degrading, three cooperative studies were conducted by the U.S. Geological Survey between 1993 and 2003. As part of these studies, water quality in the lakes was documented in 1993?94, 1996?97, and 2000?01, and water and phosphorus budgets were constructed for water year 2001. Historical water-quality data indicated that the lakes have changed little since the late 1980s. A detailed phosphorus budget indicated that most of the 14,100 pounds of phosphorus input to the lakes during 2001 came from the upstream lakes, streams draining relatively undeveloped land upstream of Hemlock Lake, and ground water. Simulation results from two water-quality models (BATHTUB and WiLMS) indicated that about a 50-percent reduction in phosphorus loading from that measured in 2001 is required for all three lakes to be classified as mesotrophic; therefore, appreciable improvements in the water quality would require improvements in the water quality of the upstream lakes. Although the water quality of the lakes has not changed appreciably in recent years and major improvements in water quality are unlikely without major improvements to upstream lakes, continued efforts to protect the susceptible watershed are necessary to maintain the current level of water quality.