The water quality of the South Basin of Long Pond, located in the Belgrade Lakes region of Maine, was investigated by the Colby Environmental Assessment Team (CEAT) from May to September of 2007. The physical, chemical, and biological characteristics of water quality were analyzed to evaluate the current health of the lake. The Long Pond South watershed was examined to investigate the effect of land-use patterns, including residential and commercial development, on the lake water quality. Data were also collected from road and shoreline surveys to produce maps highlighting areas that could potentially contribute to the degradation of water quality. Data collected during the summer and fall were compared with data from previous years to study the historic water quality trends. The water quality trends show that the lake transparency of Long Pond South has decreased by roughly one meter over the past 30 years, suggesting greater productivity. The trophic status of Long Pond South is oligotrophic, but the decreasing trend in transparency could indicate the acceleration of eutrophication. This possibility is supported by the trend of increasing pH over the past 30 years, which is linked to increased algal growth. In late summer, Long Pond South has very low oxygen levels in the temperature-defined metalimnion and near the bottom of the water column. More research is needed to determine the cause of the low-oxygen concentration in the metalimnion, but the lack of oxygen on the bottom during the summer months is likely due to stratification of the water column preventing the addition of oxygen from the surface. Existing oxygen on the bottom is then used up by the large populations of decomposers that develop because of the increased availability of sediment organic matter in aging lakes. The amount of aquatic plant productivity in a lake is limited by the amount of phosphorus in the water. The increasing productivity trend in Long Pond South indicates increasing levels of phosphorus, and if the phosphorus levels exceed 12-15 ppm an algal bloom may result. Algal blooms can be detrimental to the health of other organisms in the lake, such as fish, can decrease the aesthetic value, and can reduce the value of shoreline homes. Although the phosphorus levels in Long Pond South are not yet high enough to cause algal blooms, the increasing trend is a cause for concern.
Colby Environmental Assessment Team, Colby College and Problems in Environmental Science course (Biology 493), Colby College, "A Watershed Analysis of Long Pond South: Implications for Water Quality and Land Use Management" (2007). Colby College Watershed Study: Long Pond, South (2007, 1995). Paper 1.