SURFACE AND GROUNDWATER NITRATE DATABASES FOR SOUTHEASTERN MINNESOTA, USA

Initial results of a Minnesota Pollution Control Agency (MPCA) funded collation of nitrate databases for surface and groundwater of the 10 counties of southeastern Minnesota’s (SE MN) karst region are presented. The goal is to identify existing data that can help define time trends and mechanisms of nitrate water pollution.

The U.S. Geological Survey’s National Water Information System contains data collected from 1889 to present for the entire nation and is available on the Internet.

The MPCA created three successive state-wide ambient (background) groundwater monitoring programs, which includes nitrate data, maintained in the EPA’s STORET database: from 1978 to 1990, from 1992 to 1996, and from 2003 to present. In the current program, urban surface and groundwater are sampled by the MPCA while rural waters are sampled by the Minnesota Department of Agriculture. Another MPCA program, Milestone Rivers, has nitrate data from 1953 onwards. The Garvin Brook watershed of SE MN was studied in more detail.

The Minnesota Department of Health (MDH) began recording nitrate data from the initial testing required for the installation of new wells in 1974. Eventually these data will be linked to the County Well Index, maintained by the Minnesota Geological Survey, which includes aquifer-specific information and unique well numbers. MDH also maintains the Minnesota Drinking Water Information System, collecting nitrate data from public water systems. Another MDH effort, since 2008, is the Voluntary Nitrate Monitoring Network, unique to SE MN, which relies on citizen volunteers to sample domestic well waters.

The Minnesota Department of Natural Resources’ (DNR) Part B of the County Geologic Atlas series often includes nitrate data, available on the Internet. The DNR’s state fish hatcheries have monitored nitrate concentrations in source springs.

Smaller units of government and independent researchers have accumulated much data. The Olmsted County Regional Laboratory has more than 36,000 well-water analyses from surrounding counties. County nitrate clinics, where individuals can have well-water tested, are another large source of data. The Metropolitan Council (Twin Cities) collects surface water samples along the Mississippi River. University of Minnesota dissertations also contain much nitrate data.