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nuisance concerns impacting downstream public water systems. Examples include algal fouling. <br />Of filters at the treatmdh plant and unpleasant taste and odor in the treated drinking water. <br />• Public Health Risks Associated with Water - Body Contact Recreation and Agricultural Uses: <br />Increased concentrations of pollutants associated with point and nonpoint source discharges and <br />natural sources of contamination may result in unsafe conditions for persons in direct contact <br />with raw /untreated water. The primary acute risks would be associated with ingestion or dermal <br />contact with pathogenic organisms. The Department of Public Health and Environment should <br />increase monitoring at these sites with high public usage <br />Waste Water Treatment Systems. <br />Background: Discharge limits for a waste water treatment facility (both municipal and industrial) are <br />assigned in a discharge permit issued by the WQCD. The limits are calculated based on the ability of <br />the "receiving waters" to dilute, or attenuate, the discharge of pollutants to meet water quality standards. <br />The stretch of water below the discharge point in which this dilution takes place is termed the "mixing <br />zone." The mixing zone is based on a 10 -year low flow average. For adequate protection of designated <br />uses to occur, the volume of water in the stream needs to approximate this average low flow condition. <br />There are three primary concerns associated with severe drought conditions: <br />• Impairment of Drinking Water Treatment As mentioned above, discharges <br />from municipal waste. water treatment facilities to extreme low flow conditions would further <br />increase water temperatures, increase the nutrient content of the stream, and promote algal <br />blooms thereby increasing the costs to downstream public water systems. <br />• Public Health Issues for Downstream Recreational Users. Water -borne illnesses due to elevated <br />levels of microbial contaminants such as E. coli, Cryptosporidium and Giardia. Extreme low <br />flow conditions would cause pollutants to persist in the stream far beyond the normal mixing <br />zone and possibly into downstream recreational use areas causing water -borne illness. Primary <br />areas of concern include streams such as Bear Creek, Boulder Creek, Cherry Creek, Clear Creek <br />and the South Platte .River in Front Range population centers. <br />Industrial Discharges: Industrial dischargers could see increased concentrations of metals and <br />organics below their outfalls. Early indicators of problems could be environmental impacts such <br />as fish kills. Extreme low flows could lead to an exceedance of water quality standards with <br />potential health implications to downstream recreational users. Contaminants exceeding the <br />primary drinking water standards could pass through public water systems and not be detected <br />until the required self - monitoring of treated water occurs up to a month, quarter, or year later. <br />Environmental: <br />Background: Water quality standards are based on designated uses for a segment of stream or a lake. <br />Designated uses include: agriculture, aquatic life, recreation and water supply. Environmental impacts <br />would be associated with aquatic life and recreation: <br />• Aquatic Life. Severe drought would increase temperatures and promote the growth of algal <br />blooms. This could lead to inadequate levels of dissolved oxygen for fish populations. The algal <br />blooms could also result in increased anoxic conditions in reservoirs causing an increased release <br />