City of Boulder/USGS Water Quality Monitoring
Water Quality Index for April, 2007 at
North Boulder Creek at Boulder Falls

Grade B For April, 2007 the WQI rating at North Boulder Creek at Boulder Falls (NBC-FALLS) was Good (B) due to a WQI value of 81.72. 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 102.30 98.84 0.17 16.80
Fecal Coliform #/100 mL Data Unavailable
pH pH 7.04 88.20 0.11 9.70
Total Phosphate mg PO4/L 0.60 52.26 0.10 5.23
Nitrates mg NO3/L Data Unavailable
Turbidity NTU 11.20 71.97 0.08 5.76
Total Solids mg/l 94.00 83.23 0.07 5.83
Totals (factors, total) 0.53 43.31
Adjusted WQI 81.72

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 March at this station

WQI for May at this station

Return to WQI map for April


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Last Page Update - Tuesday June 12, 2007