Water resources are of prime importance at Pictured Rocks National Lakeshore. The park's science staff conducts annual inventory and monitoring projects to assess the overall condition of the park's inland lakes. By accumulating baseline data over many years, scientists can better understand each lake's natural features and therefore recognize changes when they happen – particularly human-caused changes that might require management action.
Continued monitoring will help staff separate trends that might arise from human origins (such as climate change, acid rain, invasive species, nutrient run-off, impacts from high recreational use, and chemical contaminants) from natural fluctuations.
Since 2007, Pictured Rocks has been part of a regional Great Lakes Network Water Quality Monitoring Protocol for Inland Lakes. Five lakes – Beaver, Legion, Chapel, Miners and Grand Sable – are tested annually for many chemical and physical parameters, including temperature, pH, dissolved oxygen, conductivity, clarity, productivity, and water level. A sixth lake, Trappers, was added in 2012.
Studies have revealed that each lake is completely unique, with its own character and natural features. Chapel Lake is extremely deep and isolated, while Beaver Lake, which was once part of Lake Superior, is shallow and sandy. Legion Lake is quite acidic and more "bog-like" compared to the others. Miners Lake is the most nutrient rich; Grand Sable is the least.
Toxic algal blooms are becoming more common throughout the Great Lakes. Though no visible surface blooms have occurred at Pictured Rocks, lakes adjacent to backcountry campsites are being tested for algal toxins as a precautionary measure.
As part of the Great Lakes Network, Pictured Rocks and other national park sites use the same testing protocols so that results may be analyzed not only for each individual park but for the Great Lakes region as a whole. The results will allow researchers to detect changes and trends on a much larger scale.