City of Boulder/USGS Water Quality Monitoring
Boulder Creek Watershed
Boulder Creek Water Quality Index

WQI at Boulder Creek above St. Vrain for June, 2000

Grade C For June, 2000, the WQI rating at Boulder Creek above St. Vrain (BC-aSV) was Medium (C) due to a WQI value of 65.5. The chart below details the WQI calulations at this site. See the detailed explanation of the WQI method for more information.

6-parameter Test result unit Q-value weight factor total
BC-aSV 6/2000          
DO 200.8 % sat 50 0.17 8.5
Fecal Coliform <10 #/100 mL 80 0.16 12.8
pH 9.53 std units 32 0.11 3.52
Total Phosphate 0.22 mg/L PO4-P 80 0.10 8
Nitrates 3.72 mg/L NO3 74 0.10 7.4
Turbidity 3.88 NTU 87 0.08 6.96
totals (factors, total)       0.72 47.18
adjusted WQI         65.5

The WQI is computed by converting measured Water Quality Parameters to "Q-Values" using charts developed by the National Sanitation Foundation (NSF) water quality scientists. The Q-Values are then multiplied by a weighting factor based on the importance of that water quality parameter.

WQI at Upstream Station: Boulder Creek Below Coal Creek

WQI at for October, 2000 at this station

Return to WQI map for June, 2000
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Last Page Update - Tuesday December 27, 2005