Quantifying gradients of anthropogenic stress can inform the development of sample designs, provide an important covariate in modeling relationships of response variables, identify reference and highly-disturbed sites, and provide a baseline and guidance to restoration and remediation efforts. We describe development of SumRel, a composite index of anthropogenic stress, for the U.S. and Canadian Lake Superior basin. Key elements of the project include development of high-resolution watersheds throughout the basin, summarization of the major point and non-point stressors within these watersheds, and creation of tools for scaling the watersheds and stressor summaries. SumRel was calculated at two spatial scales: for high resolution subcatchments within the Lake Superior basin (mean watershed area = 93 ha) and for coastal watersheds of Lake Superior. An assessment of subcatchments within Minnesota's St. Louis River watershed showed a correlation between the degree of disturbance, as indicated by SumRel, and impaired water quality, as evidenced by in-stream conductivity. These data and tools allow identification and visualization of reference and highly-disturbed sites at multiple spatial scales, providing decision support for individual agency and binational monitoring, assessment and restoration initiatives across the Lake Superior basin.
Bibliographical noteFunding Information:
Ms. Jane Reed created the website design for ‘Explore Lake Superior,’ and Mr. Gerald Sjerven served as website administrator. This work was funded in part by a grant from the U.S. EPA Great Lakes National Program Office, Grant number: GL00E28801-0. Although this research has been funded wholly or in part by the U.S. EPA, it has not been subjected to the agency’s required peer and policy review and therefore does not necessarily reflect the views of the agency and no official endorsement should be inferred. Dr. Richard Axler generously shared water quality data collected in the St. Louis River watershed; funding for this analysis was provided by the Minnesota Pollution Control Agency. The integration of the U.S. and Canadian land use classifications was funded by grants from the National Fish and Wildlife Foundation, and Environment Canada through the Lake Erie Lakewide Area Management Plan to the University of Windsor and the Lake Erie Millennium Network. This is contribution number 517 from the Center for Water and the Environment, Natural Resources Research Institute, University of Minnesota-Duluth.
- Great Lakes
- anthropogenic stressors
- environmental indicators