Paula L. Sturdevant-Rees
The Wachusett Reservoir watershed is an integral component of the Metropolitan Boston water supply. The Massachusetts Department of Conservation and Recreation (DCR) is responsible for water resource management and water quality protection and has implemented extensive environmental monitoring and modeling programs. These efforts have been used to identify and direct management priorities. Also, a long term collaborative effort with the University of Massachusetts, Amherst has focused on improving data collection and watershed modeling. From the environmental monitoring program, annual nutrient fluxes for total phosphorus (TP), nitrate (NO3-N), and total organic carbon (TOC) have been estimated. These annual nutrient fluxes have assisted DCR to direct water quality management spatially throughout the monitoring period. However, the program has had limited success in identifying the fluxes temporally due to budgetary restrictions on frequent routine sampling. In order to more effectively utilize resources, collaborative research projects with the University of Massachusetts Amherst have been funded to investigate the potential for modeling hydrological variability in the Wachusett Reservoir sub basins to more effectively utilize available data. Several methods to estimate nutrient flux were investigated to evaluate the potential to interpolate a more complete and useful nutrient and hydrologic dataset. These included multiple regression and mechanistic methods. The regression methods utilized a geographical information system (GIS) and generated nutrient loading estimates at annual and monthly timescales. Lumped mechanistic methods were used to generate daily hydrologic and nutrient loading estimates to more accurately capture temporal variability. The methods were compared to evaluate both accuracy and applicability of modeling at the various subbasins. Application of the mechanistic models toward watershed management was another goal of the modeling project. The model dataset generated was applied to optimize the DCR routine monitoring program. Several potential improvements toward watershed monitoring were recommended to more accurately capture hydrologic and nutrient loading variability in the Wachusett Reservoir Watershed.