ANTRHOPOGENIC INFLUENCE ON THE BELGRADE LAKES, MAINE, WATERSHED: A GIS APPLICATION

The Belgrade Lakes watershed includes six interconnected lakes and represents an important water, energy and recreational resource in central Maine. Over the past 150 years this watershed has been significantly modified by the construction of seven dams for water control and hydroelectric power generation. Application of GIS software to watershed and dam data allows assessment and documentation of anthropogenic impacts.

Data for each dam was obtained from the Maine Emergency Management Agency and included construction dates (1896-1989), length (6.7-76.1 m), structural height (0.1-7 m) and hydraulic height (0.3-5.5 m). Bathymetrical maps of each lake in the watershed were created using data collected in the field and were supplemented by fishing maps obtained from the Public Educational Access to Environmental Information in Maine (PEARL) website and soil survey data from the Maine GIS website. Longitude and latitude of each dam were determined in the field using GPS. A GIS mapping program was used to integrate these data and depth maps were created. Using hydraulic height values for each dam to recreate the original geographic extent, changes in lake volume (1.0 x 10⁷ to 1.4 x 10⁷ m³) and surface area (12-43%) were determined. Adding the dates of dam construction, changes in aerial extent of the lakes in the watershed were mapped in a historical context.

It is clear that this region would look significantly different had the dams not been constructed. Data also indicate that changes in lake volume and area occurred prior to 1892, based on comparison with the oldest topographic maps available. Results of this investigation provide a historical context and an important foundation for long-term hydrogeochemical and geochemical investigations of this watershed.