Highland Lake phosphorus loading study :terrain and water quality analysis through a geographic information system and empirical models

Andrews, Alexis, P.
Sidney Pilgrim
Department of Environmental Studies
Maine's lakes have been cited as one of the state's most economically viable resources. The quality of the water is a great concern to recreationalists, as well as to the concentrated population of greater Portland which uses the lake resources for drinking water. The Sebago Lake region has experienced an increased amount of growth in recent years which has led to clearing of the land for new houses, roads, and lake access. These activities have posed a serious threat to the water quality of lakes, as increased soil erosion transports a larger volume of phosphorus to the lakes. Phosphorus has been determined to be the number one threat to water quality in the Sebago Lake region, and the deterioration of the lake ecosystem would lead to a loss of one of the state's prime natural resources. The purpose of this case study is to predict through empirical modeling the amount of phosphorus exported into Highland Lake. Previous studies, both regional and local, have quantified export coefficients from stream sampling, and linked these with different land uses. This study modifies the export figures by accounting for soil, slope, and proximity factors which affect the specific figures for the given study area. Predictions of in-lake phosphorus derived from model equations are then assessed according to lake model suitability and divergence from the observed in-lake phosphorus readings.

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