Cheruvelil EPA-NLAPP 6-state lake-landscape database

Lake data were compiled for six U.S. states: Maine (N=~593), New Hampshire (N=~651), Ohio (N=~55), Iowa (N=~117), Michigan (N=~557), and Wisconsin (N=~347). Lake water chemistry were sampled from the epilimnion. Data were collected from databases maintained by state agencies responsible for monitoring lakes under the Federal Clean Water Act, which requires standard procedures and quality assurance and quality control protocols. Lakes with surface area ≥ 1 ha and maximum depth ≥ 2 m were included in the dataset. Each lake was assigned a unique identifier. We collected data on LAKES (chemistry, clarity and depth); NATURAL LANDSCAPE FEATURES (catchment area, lake elevation, and features obtained from GIS (hydrology, runoff, precip, baseflow); and HUMAN IMPACT FEATURES (Land use/cover (NLCD) in 500m buffer around lakes, roads in 500m buffer, human census data within the smallest unit available (county subdivision). We also quantified land cover, land use, groundwater hydrology, and several other geographic variables within the Ecological Drainage Unit (EDU) region. Lake data came from the following state agency sources: Maine Department of Environmental Protection, Maine Department of Inland Fisheries and Wildlife’s Lake Survey table (1/21/03); New Hampshire Department of Environmental Services; Michigan Department of Environmental Quality; Wisconsin Department of Natural Resources; Ohio Environmental Protection Agency; and Iowa State University Limnology Laboratory (Joint Iowa DNR / ISU Project). The purpose of the dataset was to investigate lake and landscape controls on lake water chemistry across broad geographic regions.