Examining Maine’s ‘classy’ water quality

    A slow-moving, murky stream flows through a shady forest. The water is shallow and warm, so you go wading, and a leech gets stuck to your foot. Ugh! Later on, you find another shady stream, this time near town: a clear stream with quick-flowing water that looks just right for fishing.
    Isn’t the second stream “cleaner”? Well, it depends on how you judge cleanliness. Maine has a water quality classification system to indicate if streams and rivers support the uses we expect them to (use as drinking water sources, for swimming, fishing, or boating). So the ability of a stream to meet its intended uses, not how it looks, determines its class. If both streams meet their assigned water quality classes, they are both places where it’s safe to swim, to catch fish (and eat them), and to drink the water if it’s properly treated or disinfected.
    In this case, the murky stream runs through a state park and is in the most protected water quality category, Class AA. The second stream, though clearer, runs though an urban area where it picks up pollutants from stormwater runoff (fertilizers and other nutrients, metals, sediments from parking lots), and it is a Class C stream. Maine isn’t all pristine wilderness, so holding all streams, rivers, and wetlands to a high standard wouldn’t be realistic. Maine’s classification system provides a legal framework for keeping our water in the highest attainable condition. A range of water quality classes, from AA to C, allows waters used for different purposes to be held to different standards.
    By law, Class AA streams, rivers or wetlands must have dissolved oxygen levels, bacterial counts, and aquatic life “as naturally occurs” and human activities are restricted. Greater allowance is made for human activities in and near Class C waters and therefore they exhibit some changes when compared to natural waters, but the biological integrity of the waterbody must be preserved. The Crooked River, whose waters drain to Sebago Lake, the drinking water supply for Portland, is Class AA. Because it is a valuable drinking water source and supports a significant fishery it receives the highest level of protection. The lower Kennebec River, which passes through Augusta, is Class B.
    Water quality classes reflect the highest attainable goals for a waterbody rather than a fixed “grade” of water quality. Maine has raised the classification for over 1,500 miles of rivers and streams as water quality has improved over the years.
    Every two years, states report to the EPA any waters that are not meeting their assigned criteria. If a waterbody does not attain its class, states must investigate and write a plan to fix the problem. Maine DEP posts its Integrated Water Quality Monitoring and Assessment Report and restoration plans on its Web site.
    For more information on Maine’s water quality classification, visit www.maine.gov/dep/blwq/docmonitoring/classification.
    This column was contributed by the Biomonitoring Program staff at the Maine Department of Environmental Protection (DEP). In Our Back Yard is a weekly column of the Maine DEP. E-mail your environmental questions to infoDEP@maine.gov or mail them to: In Our Back Yard, Maine DEP, 17 State House Station, Augusta, ME 04333.