PUB00039 - Laserfiche WebLink

Home Browse Search

I I I I I I I I I I I I I I I I I I I DOLORES RIVER VATER QUALITY IMPROVEMENT STUDY During pre-construction activities for Dawson Draw Reservoir, a proposed fish and wildlife enhancement feature of the Dolores Project, a study was conducted to determine the possibility that a water quality problem would manifest in the reservoir. The water supply for Dawson Draw would be the Dolores River, diverted from McPhee Reservoir. The primary concern was heavy metals. Biota in the Dawson Draw area and fish from surrounding reservoirs were sampled. Results showed elevated mercury level in several different species of fish from both Narraguinnep and McPhee Reservoirs. Subsequent sampling also showed elevated mercury levels in fish from Totton Reservoir. The Colorado Department of Health has posted both Narraguinnep and McPhee Reservoirs concerning the hazards of human consumption of selected fish species. The purpOSe of this study is to determine the source and quantity of heavy metals now entering the Dolores River and identify parties potentially responsible for the pollutants. The Clean Vater Act as amended and other hazardous waste laws provide a mechanism to clean up pollution sources which threaten pUblic health or the environment. A report documenting the procedures and findings of this study will be submitted to the Environmental Protection Agency and the Colorado Department of Health for funding consideration under Superfund and other cleanup programs. In the past, there was extensive mining and processing activity in the Rico area, approximately 40 miles upstream of the town of Dolores. There are numerous mine waste, drainage, and mill tailings sites in the area. Two sites have historically introduced fluctuating amounts of heavy metals to the Dolores River: 1) The sulfuric acid production site along the Dolores River just above Rico and 2) the Rico Mill site on Silver Creek east of Rico. Vhile these two site still contribute heavy metals to the Dolores River, investigations have identified other pollution sources. Preliminary data collection begin in 1989 with the collection and analysis of water and sediment samples from eleven locations on the Dolores River, major tributaries, and near mining activity sites. Date collection was expanded in 1991 and 1992 to include additional water sampling locations and sampling of fish and biota in the Dolores River. Thus far, the results have shown a definite contribution of heavy metals from some of the mining activity sites but have also identified what appear to be natural, diffuse sources of heavy metals pollution. Ve are currently working to quantify the loading of heavy metals from each known pollution site and investigating the diffuse sources. The study will be completed in 1993 and the final report should be available in early 1994.