PurposeThe National Lakes Assessment (NLA) is the first-ever baseline study of the condition of the nation’s lakes. It is the latest in a series of surveys of the nation’s aquatic resources being conducted by EPA and its state and tribal partners. The NLA provides unbiased estimates of the condition of natural and man-made freshwater lakes, ponds, and reservoirs greater than 10 acres and at least one meter deep. Using a statistical survey design, lakes were selected at random to represent the condition of the larger population of lakes across the lower 48 states. A total of 1,028 lakes were sampled for the NLA during summer 2007, representing the condition of about 50,000 lakes nationwide. The Great Lakes and Great Salt Lake were not included in the survey. Field crews collected samples using the same methods at all lakes to ensure that results can be compared across the country. Researchers processed and analyzed 680,000 measurements, including indicators of water quality such as nutrients, dissolved oxygen and algal density; biological indicators such as phytoplankton and zooplankton (algae and microscopic animals); recreational indicators such as algal toxins and pathogens; and physical habitat indicators such as lakeshore and shallow water habitat cover.
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Aquatic Plant Monitoring or Survey