A water quality analysis of the Blodgett Brook watershed

Mills, David H.
Michael Simpson, MS
Department of Environmental Studies
The Blodgett Brook watershed was examined to determine potential sources of water quality problems and their effect on Lake Sunapee. Given that this watershed represents less than 1.0% of the total Lake Sunapee Watershed area but 8.0% of the total stream volume input, its effect on the Lake Sunapee is disproportionate to its size. This, combined with the presence of a large number of septic systems in the watershed, makes this watershed one of concern to the Lake Sunapee Protective Association and other lake advocates. Between September and December, 1994, water samples from eight sites were analyzed. Very low alkalinities and high average phosphorous values were the principle water quality problems detected. The Blodgetts Landing treatment plant appears to be a significant contributor of phosphates and nitrates in the watershed. Upgrading this treatment plant or replacing it by connecting Blodgetts Landing to the treatment plant in Sunapee is recommended. Macroinvertebrate collections from two sites at the lower reaches of Blodgett Brook indicate that this stream has a slight to moderate degree of organic pollution. While a significant portion of the Blodgett Brook watershed remains protected, the potential for development within this watershed is significant. A build out analysis was done for the watershed to determine the effect maximum development of the watershed would have on Lake Sunapee. The analysis indicates that there would be a three fold increase in sewage loading and in phosphorous loading into Lake Sunapee from Blodgett Brook. The Build out analysis figures assumed year round usage.

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