Land use is an important parameter in the assessment of coastal waters, as land-based activities and land-based pollution affect the quality of downstream environments. Land uses and land-use change around Mussel Watch Program monitoring sites in the Great Lakes are poorly understood. We characterized land use around these sites to improve our interpretation of Mussel Watch Program water quality monitoring data.

Why We Care
Land-use practices and activities can have a profound effect on the quality of freshwater and coastal ecosystems, making these land-based parameters important factors in assessments of nearshore environments.

What We Did
We compiled land-use data for 54 Mussel Watch Program (MWP) water quality monitoring sites in the Great Lakes. We generated maps and land-use data for each MWP site from spatially and thematically consistent National Land Cover Database raster layers and base maps for three distinct periods (1992, 2001, and 2006), orthoimagery data sets, decennial 1970 to 2010 census population data, and geographic data on major and minor permitted facilities in the U.S. EPA’s National Pollutant Discharge Elimination System. We assigned each MWP site to one of four mutually exclusive land-use categories: agriculture, undeveloped, urban, and low-developed.

Benefits of our Work
No prior attempt has been made to report on land use around the Great Lakes Mussel Watch sites. This characterization and assessment of land use around MWP sites yielded new land-use data and maps that will help in the interpretation of contaminant monitoring data, including: identifying pollution gradients and temporal and spatial contaminant patterns among different land-use categories, and identifying land-use tipping points associated with water quality impairment within MWP sites and associated nearshore watersheds. This product will enhance the information shared by the Mussel Watch Program, allowing coastal managers and policymakers to make informed decisions about nearshore resources in the Great Lakes.