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<br />tivity, and nutrient concentrations have got- <br />ten worse between 1979 and 1991, due to <br />development in the Vail area. The table below <br />lists some of the parameters that have <br />increased thereby decreasing water quality. <br /> <br />Natural Sediments <br />A significant source of sediment, which <br />smothers aquatic life and reduces habitat, <br />comes from the Milk, Alkali, and Ute Creek <br />drainages. This is due to the highly erosive <br /> <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br /> <br />Table 3. Sample of Water Quality Trends <br /> <br />Parameter <br /> <br />1979 <br /> <br />1991 % Change <br /> <br />+8% <br /> <br />Dissolved Solids (milligrams per liter) <br />Salt Concentrations (conductivity measured in microhms) <br />Nutrients (ex. Phosphorus in milligrams per liter) <br /> <br />178 <br />270 <br />0.18 <br /> <br />192 <br />305 <br />0.26 <br /> <br />+44% <br /> <br />+13% <br /> <br />These trends are most likely also occurring <br />around all the urbanizing areas of the Eagle <br />River watershed. Further degradation of <br />water quality from stormwater runoff could <br />occur in all areas subject to development <br />unless mitigating steps are taken. <br /> <br />Metals <br />Although metal concentrations in the Eagle <br />River downstream of the Eagle Mine have <br />significantly improved, fish and aquatic <br />insects are still impacted by mine discharges <br />as far down as Edwards. For example, the <br />water quality standard for zinc to protect <br />aquatic life is approximately 0.12 milligrams <br />per liter (mg/l), while levels in the Eagle River <br />below Cross Creek were as high as 0.52 mg/l <br />on February 21, 1995. <br /> <br />Increased Temperature <br />Lower in the Eagle River, from Edwards to <br />Wolcott, and from Eagle to Gypsum, fish have <br />died periodically of furunculosis, as docu- <br />mented by the Colorado Division of Wildlife. <br />This and other diseases have impacts of such <br />magnitude only when the fish are already <br />stressed due to due to poor water quality, <br />increased water temperature (caused for <br />example by low water levels or part loss of <br />stream side shading), and habitat disturbance <br />and destruction. <br /> <br />32 <br /> <br />~-. <br />,J <br />( - <br />.~ ~ <br /> <br />soils and steep slopes which are easily <br />washed into the creeks during spring <br />snowmelt and runoff from rain storms. This <br />area (approximately 63 square miles) is also <br />estimated to contribute 2,600 tons of salt to <br />the Colorado River each year. <br /> <br />Land Use Impacts on <br />Water Quality <br /> <br />Nutrients (Le. nitrogen and phosphorus) <br />increases promote algal blooms which are <br />unsightly and can lead to fish kills because of <br />reduced oxygen leading to suffocation. Trout <br />are extremely sensitive to un-ionized ammo- <br />nia (one form of nitrogen), and will die when <br />exposed to levels above 0.02 mg/l. Nutrient <br />sources include lawn fertilizers, septic sys- <br />tems, and eroding soils. There are numerous <br />mitigating measures which can be used to <br />reduce nutrient inputs to water bodies, <br />including: better education on application of <br />fertilizers; erosion control techniques; <br />stormwater quality improvement projects; <br />land use setbacks; protection of wetlands; <br />and septic system inspection and mainte- <br />nance. <br /> <br />Increases in sediment in the water increase <br />turbidity, increase water treatment costs, <br />