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

Grade B For September, 2006 the WQI rating at North Boulder Creek at Boulder Falls (NBC-FALLS) was Good (B) due to a WQI value of 76.61. 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 94.20 96.73 0.17 16.44
Fecal Coliform #/100 mL 20.00 61.54 0.16 9.85
pH pH 6.75 79.34 0.11 8.73
Total Phosphate mg PO4/L 0.03 98.23 0.10 9.82
Nitrates mg NO3/L Data Unavailable
Turbidity NTU 5.86 82.79 0.08 6.62
Total Solids mg/l 641.00 20.00 0.07 1.40
Totals (factors, total) 0.69 52.86
Adjusted WQI 76.61

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 August at this station

WQI for October at this station

Return to WQI map for September


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Last Page Update - Thursday March 01, 2007