Phosphorus loading and water quality in Lake Simcoe
Ann Arbor, MI — Phosphorus loads to Lake Simcoe, Canada are estimated to now be less than its target load goal. However, despite some improvements in water quality, efforts to reduce phosphorus loads need to continue.
Located 50 km north of Toronto, Lake Simcoe is a little more than an hour's drive from half the population in Ontario. The lake is home to one of the most intensive inland sport fisheries in the province, however, wild populations of cold water fish such as lake trout have been virtually extinct since the late 1980s due to excess phosphorus in the lake.
"Phosphorus loads to Lake Simcoe from inflowing tributaries and sewage treatment plants have decreased significantly since the early 1990s," says Jennifer Winter, a Research Scientist with the Ontario Ministry of the Environment. "We've also observed some improvements in dissolved oxygen levels in the lake, and there has been some evidence of natural reproduction in cold water fish populations."
Since 1991, the Lake Simcoe Environmental Management Strategy (LSEMS) has focused on reducing the levels of phosphorus entering the lake to improve water quality and to support a self-sustaining community of cold water fish. Although phosphorus concentrations have decreased significantly in several rivers flowing into the lake, present-day concentrations are still above the level recommended to avoid nuisance plant growth. Excessive growths of filamentous algae and aquatic plants continue to be a problem in shoreline areas of the lake, and deep-water dissolved oxygen concentrations at the end of the summer remain below the level that is considered protective of lake trout. The coldwater fish populations are currently maintained through stocking, and natural reproduction remains low. Clearly, initiatives to reduce phosphorus loading to Lake Simcoe should continue.
Original Publication Information
Results of this study, "Phosphorus Inputs to Lake Simcoe from 1990 to 2003: Declines in Tributary Loads and Observations on Lake Water Quality," are reported by Jennifer G. Winter, M. Catherine Eimers, Peter J. Dillon, Lem D. Scott, Wolfgang A. Scheider and Campbell C. Willox in the latest issue (Volume 33, No. 2, pp. 381-396) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2007.
Contacts
For more information about the study, contact Jennifer Winter, Ontario Ministry of the Environment, Environmental Monitoring and Reporting Branch, 125 Resources Road, Toronto, ON M9P 3V6, Canada; Jennifer.Winter@ontario.ca, (416) 327-3715.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; editor@iaglr.org; (608) 692-1076.
Links
Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.