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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lCRA

Fiul _It. PIwe \ ..-...... Water 0aaIiIv Data Colle<doa Smdv

tW-nfQnlber 1995

The monthly water quality sampling included the parameters shown in Table 2. Of particular
note in the water quality analyses were the phosphorus analyses (total phosphorus, total dissolved
phosphorus and soluble reactive phosphorus) and the nitrogen analyses (ammonia and nitrate).

Throughout the study period, there were virtually no ammonia-nitrogen concentrations detected
at any of the surface water stations at any of the monthly sampling periods.

However, nitrate-nitrogen concentrations were observed at all of the surface water sampling
stations at concentrations varying from non-detectable (less than 0.05 milligrams per liter
(mg/L)) to a maximum of 1.2 mglL (observed at CC-4 in August 1994). A plot showing the
l2-month average, the maximum and the minimum nitrate-nitrogen concentrations at each of the
surface water sampling stations is shown in Figure 6.

Nitrate-nitrogen concentrations increase from CC-2 to CC-4, however, this is followed by a
decrease in concentrations from CC-4 through CC-8. Overall, the l2-month average nitrate-
nitrogen concentrations changed from approximately 0.12 mg/L at CastIewood Canyon \00.38
mg/L going into Cherry Creek Reservoir.

Similar data are presented for total phosphorus and soluble reactive phosphorus (SRP)
concentrations at each of the surface water sampling stations (Figure 6). Of particular note in
these plots is the fact that, while phosphorus concentrations increase in the reach between
CastIewood and Cherry Creek Reservoir for both total phosphorus and SRP concentrations, the
l2-month average phosphorus concentrations at Cherry Creek Reservoir are approximately equal
to those observed at CastIewood Canyon (above all point discharges in the upper Cherry Creek
Basin). The 12-month average SRP concentrations at CastIewood and the Reservoir are identical
(0.13 mg/L), while the 12-month total phosphorus concentration was 0.17 mg/L at CastIewood
and 0.19 mg/L at the Reservoir.

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