Lake Water Quality Assessment Monitoring ProgramContact: Sarah Holden 517-342-4083
In 1997, the DEQ completed a report entitled "A Strategic Environmental Quality Monitoring Program for Michigan's Surface Waters" (Strategy). This Strategy describes the monitoring activities that are necessary for a comprehensive assessment of water quality in Michigan's surface waters. One component of the Strategy is the continuation of a statewide ambient water quality monitoring program for Michigan's inland lakes.
Historically, the DEQ and the Department of Natural Resources (DNR) monitored water quality in Michigan's lakes and streams. In 1973 the former DNR began systematically inventorying and sampling lakes to document trophic conditions as well as to obtain general baseline water quality information. In 1979, U.S. Environmental Protection Agency (EPA) funds were awarded to Michigan to expand the lakes monitoring effort and an ambient water quality monitoring program was initiated to sample and classify 729 public access lakes across the state. In 1998 with the support of Clean Michigan Initiative (CMI) funds the Lake Water Quality Assessment (LWQA) monitoring program was implemented in cooperation with the U.S. Geological Survey (USGS) - Michigan District as part of the DEQ's Strategic Environmental Quality Monitoring Program for Michigan Surface Waters.
The LWQA monitoring program continued the ambient water quality monitoring effort initiated in 1979 for public access lakes across the state. The primary objectives of the LWQA monitoring program were:
- Determine the trophic conditions of the inland lakes in the state
- Identify waters that are high quality, as well as those that are not meeting water quality standards
- Determine whether inland lake water quality is changing with time
- Identify emerging problems through inland lake quality assessments
- Support DEQ watershed and lake management programs for protecting inland lake quality in the state
From 2001 - 2010, 866 lake basins from 729 public access lakes were monitored for baseline water-quality conditions and trophic status. Lake water quality assessment surveys were conducted during spring turnover and summer stratification periods. The surveys were coordinated with the DEQ Water Resource Division's watershed permitting cycle. Water quality parameters monitored include nutrients (various forms of nitrogen and phosphorus), chlorophyll a, water clarity (Secchi depth), color, dissolved oxygen, water temperature, specific conductance, pH, alkalinity, hardness, and major ions such as calcium, magnesium, sodium and chloride.
In about 75 percent of inland lake deep basins, trophic characteristics were associated with oligotrophic or mesotrophic conditions; 5 percent or less were categorized as hypereutrophic and 80 percent of hypereutrophic lakes had a maximum depth of 30 feet or less. These data are used to satisfy federal CWA Sec. 314 and 305(b) requirements, determine water quality standards and designated use impairments, and to support watershed and lake management programs for protecting inland lake quality. The LWQA monitoring program is integrated with the citizen volunteer Cooperative Lakes Monitoring Program (CLMP) to increase monitoring effectiveness.
As part of the LWQA monitoring program, the USGS under the direction of the DEQ used Landsat satellite imagery for the periods of 2003-2005 and 2007-2008 along with LWQA and CLMP water clarity data to predict the trophic state of inland lakes greater than 20 acres in size.
Statistical models and an on-line application tool for predicting lake water clarity and chlorophyll content were developed and tested with LWQA and CLMP data.
The LWQA monitoring program data are stored in the USGS National Water Information System (NWIS). The predicted water clarity of approximately 4000 inland lakes is now available on an interactive map on the USGS website.
Michigan Lakes: An Assessment of Water Quality (5-Year Cumulative Report)