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

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

Grade C For October, 2000, the WQI rating at Boulder Creek above St. Vrain (BC-aSV) was Medium (C) due to a WQI value of 58.6. 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 10/2000          
DO 199 % sat 50 0.17 8.5
Fecal Coliform 2 #/100 mL 90 0.16 14.4
pH 9.58 std units 26 0.11 2.86
Total Phosphate 0.479 mg/L PO4-P 60 0.10 6
Nitrates 24.04 mg/L NO3 34 0.10 3.4
Turbidity 3.1 NTU 88 0.08 7.04
totals (factors, total)       0.72 42.2
adjusted WQI         58.6

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 June, 2000 at this station

Return to WQI map for October, 2000
Thank You! BASIN was a community project which benefitted from over 1000 hours of public volunteer time. BASIN was highlighted by the US EPA in a national case study in its 2001 handbook Delivering Timely Environmental Information to Your Community. Thank you to all volunteers, and especially to the late Jim Waterman, BASIN Project Coordinator!
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Last Page Update - Tuesday December 27, 2005