City of Boulder/USGS Water Quality Monitoring
Water Quality Index for October, 2002 at
North Boulder Creek at Boulder Falls

Grade B For October, 2002 the WQI rating at North Boulder Creek at Boulder Falls (NBC-FALLS) was Good (B) due to a WQI value of 87.25. The chart below details the WQI calulations at this site. See the detailed explanation of the WQI method for more information.


Parameter Unit Parameter Value Q-value Weight Factor Total
DO% % sat 95.60 97.21 0.17 16.53
Fecal Coliform #/100 mL 20.00 61.54 0.16 9.85
pH pH 7.17 91.15 0.11 10.03
Total Phosphate mg PO4/L 0.07 95.32 0.10 9.53
Nitrates mg NO3/L 0.10 97.90 0.10 9.79
Turbidity NTU 2.50 91.31 0.08 7.30
Total Solids mg/l 83.00 84.35 0.07 5.90
Totals (factors, total) 0.79 68.93
Adjusted WQI 87.25

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. These values are totaled and then divided by the sum of the weight factors.

WQI at Upstream Station: North Boulder Creek diversion to Lakewood

WQI at Downstream Station: Boulder Creek at Orodell

WQI for September at this station

WQI for November at this station

Return to WQI map for October


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