City of Boulder/USGS Water Quality Monitoring
Water Quality Index for September, 2002 at
Middle Boulder Creek Above North Boulder Creek Confluence

Grade B For September, 2002 the WQI rating at Middle Boulder Creek Above North Boulder Creek Confluence (BC-aNBC) was Good (B) due to a WQI value of 75.47. 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 96.10 97.54 0.17 16.58
Fecal Coliform #/100 mL 490.00 23.85 0.16 3.82
pH pH 7.10 90.00 0.11 9.90
Total Phosphate mg PO4/L 0.18 91.29 0.10 9.13
Nitrates mg NO3/L 0.10 97.90 0.10 9.79
Turbidity NTU 18.00 61.48 0.08 4.92
Total Solids mg/l 136.00 78.39 0.07 5.49
Totals (factors, total) 0.79 59.62
Adjusted WQI 75.47

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: Middle Boulder Creek at PSCo Weir

WQI at Downstream Station: North Boulder Creek diversion to Lakewood

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 - Saturday December 24, 2005