Monitoring water quality of inland lakes, 2008: Annual summary report

Elias, Joan

The Great Lakes Inventory and Monitoring Network monitored water quality of inland lakes at six national park units in 2008: Voyageurs National Park (VOYA), Apostle Islands National Lakeshore (APIS), Isle Royale National Park (ISRO), Pictured Rocks National Lakeshore (PIRO), Indiana Dunes National Lakeshore (INDU), and Sleeping Bear Dunes National Lakeshore (SLBE). The primary objective of this monitoring program is to monitor water quality in order to describe the current status and trends of common limnological parameters within sampled lakes. We hope to be able to provide early warnings of change, which may then provide justification for increased monitoring, research, or management action. Thirty-three index lakes were sampled three times during the open water season in 2008. Field measurements included depth profiles of temperature, pH, conductivity, and dissolved oxygen; water clarity; and water level relative to a benchmark. Water samples were collected for laboratory analyses of nutrients (total phosphorus, total nitrogen, nitrate+nitrite-nitrogen, ammonium-nitrogen, dissolved silica), major ions (calcium, sodium, magnesium, potassium, sulfate, chloride), dissolved organic carbon, alkalinity, and chlorophyll-a. Results from 2008 are compared across parks; individual park results are included in appendices. Results show that many lakes exceed the U.S. Environmental Protection Agency (USEPA) water quality reference criteria for their ecoregion. Calculations of trophic state indices show most index lakes to be mesotrophic. Water levels generally declined over the course of the season. Park specific comments and recommendations relating to the sampling season are provided. We expect monitoring to continue in 2009 at the same index lakes, with additional sites included as funding permits.

Monitoring water quality of inland lakes, 2008: Annual summary report

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