Water Quality Variations and Trends in Monument and Fountain Creeks

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0135 EXPLANATION 1977-88 Period of record 209 Number of values o Far out value (greater than 3 times IQR from the box) ❑ Outside value (greater than 1.5 times IQR from the box) Largest value within 1.5 times IQR of the box m o) c m 75th percentile (upper quartile) N -- d Median C— D - 2 CD c 25th percentile (lower quartile) Smallest value within 1.5 times IQR of the box Figure 2. -- Example diagram of a box plot. Median values of instantaneous streamflow (fig. 3) were larger down- stream on Monument Creek, and were larger downstream on Fountain Creek to Fountain Creek below CSWWTP. Streamflow was smaller at downstream stations on Fountain Creek because of irrigation withdrawals in this reach (Edelmann and Cain, 1985). Median values of specific conductance (fig. 4) and median concentrations of dissolved chloride (fig. 11) and dissolved sulfate (fig. 12) were larger downstream on both creeks probably because of increasing urbanization, which increased wastewater effluent and urban runoff along Monument Creek (Edelmann, 1990, p. 15) and ground -water inflow and irrigation- return flow along Fountain Creek (Cain and Edelmann, 1986, p. 8). Median pH values (fig. 5) were smaller at station 07105530 Fountain Creek below CSWWTP. Median values of temperature (fig. 6) generally were higher downstream, and median dissolved- oxygen concen- trations (fig. 7) generally were smaller downstream because of warmer stream temperatures. Median dissolved - oxygen concentrations were smaller downstream from the wastewater- treatment plant at Colorado Springs probably because of the smaller dissolved - oxygen concentrations in the effluent.