City of Boulder/USGS Water Quality Monitoring
Water Quality Index for April, 2005 at
North Boulder Creek at Boulder Falls

Grade B For April, 2005 the WQI rating at North Boulder Creek at Boulder Falls (NBC-FALLS) was Good (B) due to a WQI value of 88.65. 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 91.40 94.78 0.17 16.11
Fecal Coliform #/100 mL Data Unavailable
pH pH 6.89 83.61 0.11 9.20
Total Phosphate mg PO4/L 0.06 97.26 0.10 9.73
Nitrates mg NO3/L Data Unavailable
Turbidity NTU 8.70 76.56 0.08 6.12
Total Solids mg/l 93.00 83.23 0.07 5.83
Totals (factors, total) 0.53 46.99
Adjusted WQI 88.65

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 - Saturday December 24, 2005