City of Boulder/USGS Water Quality Monitoring
Water Quality Index for May, 2007 at
Boulder Creek at 61st St.

Grade B For May, 2007 the WQI rating at Boulder Creek at 61st St. (BC-61) was Good (B) due to a WQI value of 83.63. 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 104.90 98.51 0.17 16.75
Fecal Coliform #/100 mL 20.00 61.54 0.16 9.85
pH pH 8.02 86.56 0.11 9.52
Total Phosphate mg PO4/L 0.04 97.26 0.10 9.73
Nitrates mg NO3/L Data Unavailable
Turbidity NTU 6.20 81.97 0.08 6.56
Total Solids mg/l 157.00 75.81 0.07 5.31
Totals (factors, total) 0.69 57.70
Adjusted WQI 83.63

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 at Eben G. Fine Park

WQI at Downstream Station: Boulder Creek above WW Plant

WQI for April at this station

WQI for June at this station

Return to WQI map for May


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Last Page Update - Tuesday June 12, 2007