USE OF UNCERTAIN OR LOW COST DATA TO CHARACTERIZE THE SUBSURFACE HYDROLOGY OF THE BLUE RIVER WATERSHED, COLORADO

Watershed scale hydrologic and pollutant transport modeling is becoming a widely used tool of community planners, developers and regulators, to aid in decision making for land use and land development permitting. It is also being used to evaluate the impact of anthropogenic effects on water quality. Defining the necessary model-input parameters, which allow for accurate creation of site specific models, is difficult due to the scarcity or uncertainty of publicly available data. This is particularly true when attempting to define complex groundwater systems and subsurface hydrologic processes. Publicly available data may include: state compiled water well logs, geologic maps, and various local water quality and quantity assessments. For this research, a statistical analysis of publicly available data for the Blue River Watershed, located in the central Colorado Rocky Mountains, has been complied to aid in the definition of the groundwater regime. Evaluation was focused on two locations within the watershed: (1) Frisco Terrace, established in the 60's and 70's near the discharge into to Dillon Reservoir; and (2) Blue River Estates a relatively new development, built along a tributary in the upper reaches of Blue River. The data analyzed included: water level analysis, and subsurface lithologic records from state engineers water well installation logs, ground water level comparisons with respect to the stream and surface water elevations, and basic water quality assessments. These preliminary analyses have indicated that the groundwater aquifer: used for drinking water, and the surface water of this watershed, are connected. It is important for the city and community planners in this area to be aware of these interactions, as more development in these mountain communities is established and the potential for anthropogenic impacts to the groundwater (drinking water) aquifer is increased through processes such as wastewater outfall and storm runoff impact.