City of Boulder/USGS Water Quality Monitoring
Water Quality Index for May, 2006 at
North Boulder Creek at Boulder Falls

Grade A For May, 2006 the WQI rating at North Boulder Creek at Boulder Falls (NBC-FALLS) was Excellent (A) due to a WQI value of 91.12. 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 106.20 98.35 0.17 16.72
Fecal Coliform #/100 mL Data Unavailable
pH pH 6.89 83.61 0.11 9.20
Total Phosphate mg PO4/L 0.05 97.26 0.10 9.73
Nitrates mg NO3/L Data Unavailable
Turbidity NTU 4.74 85.57 0.08 6.85
Total Solids mg/l 96.00 82.90 0.07 5.80
Totals (factors, total) 0.53 48.29
Adjusted WQI 91.12

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 April at this station

WQI for June at this station

Return to WQI map for May


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Last Page Update - Thursday March 01, 2007