The goal of the Survey is to address two key questions about the quality of the nation's lakes and reservoirs:

• What percent of the nation's lakes are in good, fair, and poor condition for key indicators of trophic state, ecological health, and recreation?

• What is the relative importance of key stressors such as nutrients, bacteria and lakeshore development?

The Survey used a probability-based sampling design which will provide statistically valid estimates of the condition of all lakes that share similar physical characteristics.  The Survey was not designed to provide individual lake assessments to address conditions at particular lakes.

Nationally, 909 lakes, representing five size classes and distributed evenly across the lower 48 states, were included in the Survey.  The lakes were selected randomly and included natural and man-made freshwater lakes, ponds, and reservoirs that were at least 1 meter (3.3 feet) deep and 10 acres in size.

Initially, 29 Michigan lakes were randomly chosen as a part of the statistically-based national Survey.  The DEQ added 21 additional randomly chosen lakes to the survey effort for a total of 50 Michigan lakes to allow for state-based assessment.  Michigan's Survey lakes ranged from an unnamed 10 acre "lake" in Clare Co. to 13,000 acre Gogebic Lake, Gogebic Co.

The following water quality indicators were sampled at each lake:

Trophic Indicators

• Lake profiles (dissolved oxygen, temperature, conductivity, and pH)
• General water chemistry and nutrient concentrations
• Chlorophyll a, water clarity (Secchi depth), turbidity and color

Ecological Integrity Indicators

• Sediment diatoms
• Phytoplankton
• Zooplankton
• Shoreline physical habitat conditions
• Macroinvertebrates

Recreational Indicators

• Pathogen indicator (enterococci bacteria)
• Algal toxin (microcyctins)
• Sediment and water mercury

Data from the Survey will be analyzed and compiled by EPA and partnering agencies in 2008, with a final report issued in 2009.  The Survey data will be stored in the EPA data-management system STORET.  The DEQ will separately analyze Michigan's 50 lake data set for an evaluation of the condition of Michigan's inland lakes based on the national Survey assessment tools.

Related Links

EPA's Survey of the Nation's Lakes

Survey of the Nation's Lakes: Introductory Fact Sheet

Survey of the Nation's Lakes: A Fact Sheet for Communities

Survey of the Nation's Lakes - Field Operations Manual

Inland Lakes in Michigan Participating in EPA National Lake Survey