City of Boulder/USGS Water Quality Monitoring
Water Quality Index for April, 2007 at
Boulder Creek Below Coal Creek

Grade C For April, 2007 the WQI rating at Boulder Creek Below Coal Creek (BC-bCC) was Medium (C) due to a WQI value of 61.48. 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 110.00 40.87 0.16 6.54
pH pH 8.10 84.59 0.11 9.30
Total Phosphate mg PO4/L 1.37 30.00 0.10 3.00
Nitrates mg NO3/L Data Unavailable
Turbidity NTU 13.60 67.21 0.08 5.38
Total Solids mg/l 544.00 20.00 0.07 1.40
Totals (factors, total) 0.69 42.42
Adjusted WQI 61.48

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: Boulder Creek Above Coal Creek

WQI at Downstream Station: Middle Boulder Creek @ Nederland WTP

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