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from Monument Creek, and effluent from wastewater-treatment plants, The effect of effluent from wastewater-treatment plants on water temperatures of Lower Fountain Creek is shown in figure 10. The minimum water temperature measured at all sites was 0 DC except for three sites located between river miles 18 and 30, These sites are located in the stream reach in which the water consists mostly of wastewater discharged to Fountain Creek by five wastewater-treatment plants. The minimum water temperature measured in this reach was 4 DC at F28 and 6 DC at F19 and F20, As water temperature increases during the summer (fig. 11), the stream may become odoriferous because of increased volatility of odor-causing compounds, especially in the stream reach that is laden with wastewater. Warmer temperatures also aid in waste assimilation, thus increasing demands on the dissolved-oxygen resources of the stream. Specific Conductance Specific conductance of Fountain Creek generally increases downstream as the stream flows from the mountains through residential, commercial, indus- trial, and agricultural areas (fig, 12). Dissolved-solids concentrations, as represented by specific conductance, at site F12 usually are small because the streamflow consists mostly of water that drains a part of the Rampart Range, which generally is unaffected by man and is composed mostly of igneous and metamorphic rocks that resist chemical weathering, Median specific conduct- ance of Fountain Creek increases by a factor of about 2 from site F12 (341 ~S/cm) to site F17 (658 ~S/cm), probably because of urbanization, ground-water discharge, the city of Colorado Springs diversion that decreases dilution, inflow from Monument Creek, and mine tailings located adjacent to the stream and upstream from the confluence with Monument Creek. Between sites F17 and F66, the median specific conductance increased from 658 to 1,750 ~S/cm, probably as the result of discharge from wastewater-treatment plants and irrigation-return flows and, probably to a lesser extent, from tributary inflow. The variations in specific conductance of Fountain Creek increase downstream as a result of greater variations in flow and differences in sources of flow. Monthly variations in the specific conductance of Fountain Creek at sites F12, F17, and F36 are summarized in figure 13, Specific-conductance measure- ments made at site F12 indicate that dissolved-solids concentrations are smallest during the summer when streamflow is large and that dissolved-solids concentrations are largest during the winter when streamflow is small. The seasonal variations in specific conductance at sites F17 and F36 are dis- similar from those at site F12. At sites F17 and F36, the smallest specific conductance occurs during summer; however, the largest specific conductance may occur during any season, depending on flow and sources of flow, pH The median pH of Fountain Creek ranges from 7,4 at sites F19 and F20, which are located about 2 mi downstream from the Colorado Springs Wastewater Treatment Plant, to 7.9 at site F66 located at Pueblo (fig, 14), All pH measurements made on Fountain Creek have been within the acceptable range of 6.5 to 9,0 established by the Colorado Department of Health (1982), which 24