National Lakes Assessment Survey - Michigan LakesContact: Sarah Holden 517-342-4083
In 2006, the EPA and its state, tribal, federal, and other partners began implementing a series of surveys of the quality of the nation's lakes, rivers and streams, wetlands, and coastal waters (including the Great Lakes). The probability-based surveys are designed to provide nationally consistent and scientifically defensible assessments of our nation's waters and can be used to track changes in condition over time. The National Lakes Assessment Survey was designed to help the EPA provide regional and national estimates of the condition of lakes, as well as statewide assessments for those states who participated in the Survey.
The goal of these Surveys is to address two key questions about the quality of the nation's lakes and reservoirs (not including the Great Lakes):
- 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 in 2007, 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. EGLE added 21 additional randomly chosen lakes to the survey effort for a total of 50 Michigan lakes to allow for state-based assessment.
The second National Lakes Assessment survey was conducted in 2012. A total of 904 natural and man-made lakes, ponds, and reservoirs that were at least 1 meter (3.3 feet) deep and over 25 acres in size across the lower 48 states were included in the survey. In order to allow for a state-based assessment sampling was conducted at 53 randomly selected Michigan lakes.
The following water quality indicators were sampled at each lake:
- 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
- Aquatic Invasive Species
- Sediment diatoms
- Shoreline physical habitat conditions
- Algal toxin (microcyctins)
- Sediment mercury
- Triazine pesticides
The following includes a link to EPA's web page where the 2007 NLA report, data, and fact sheet are available along with specific details and status of the 2012 NLA project. The results of the 2007 Michigan assessment are also included in the links to the fact sheet and report.