WSP10010

• File Number: 8449.700
• Description: Cherry Creek
• State: CO
• Basin: South Platte
• Date: 9/1/1995
• Author: Halepaska & Assoc.
• Title: Phase 1 Baseline Water Quality Data Collection Study for the Upper Cherry Creek Basin - Final Report
• Water Supply Pro - Doc Type: Publication

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JCHA

FDW R."'lrt. _ I U_ Water 00a6tv Data CoDecti"" Stadv

SeDlm1ber 1995

MW-l to an average of 581bslday at MW-9 (Figure 10), this is principally related to an increase
in flow, and not increases in nitrate-nitrogen concentrations being input along the study reach.

Unlike nitrate-nitrogen concentrations, total dissolved phosphorus and SRP concentrations were
lower going into Cherry Creek Reservoir than those observed at the most upstream station (MW-
I). The mean total dissolved phosphorus concentration at MW-l was 0.22 mg/L, while the
average concentration entering the reservoir was approximately 0.18 mglL (MW-9), while the
SRP concentration at MW-I averaged 0.22 mg/L, and underflow entering Cherry Creek
Reservoir averaged 0.17 mg/L (MW-9) (Figure 9).

While both the total dissolved phosphorus and SRP concentrations were greater on the upstream
end of the reach than at the downstream end of the reach, the loads entering the reservoir
actually increased from the upstream end to the downstream end (Figure 10), based on the
increase in alluvial underflow. As shown in Figure 10, the total dissolved phosphorus loading
at MW-l was approximately 3.1 pounds per day (lbslday), while the total dissolved phosphorus
loading entering the reservoir was approximately 4.7 Ibslday. Likewise, the SRP loading
increased from the upstream end of the reach to the downstream end of the reach, with
approximately 3.0 Ibslday being input at MW-l and 4.3 lbslday being input at the reservoir
(MW-9)(Figure 10)(Appendix E).

In general, the range of water quality values over the study period at each station is much less
than the ranges observed in the surface water. This may be due to the small flow variation, the
slow movement of the ground water and the adsorptive capacity of the sediments and
phreatophytes to limit concentration changes.

Field water quality parameter data collected at the time of each of the monthly samplings are
presented in Appendix D (Table D-2). Ground water temperatures showed less fluctuation than
the surface water, but did indicate seasonal variations typical of shallow alluvial aquifers. The

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