City of Boulder/USGS Water Quality Monitoring
Water Quality Index for April, 2002 at
Boulder Creek at 61st St.

Grade B For April, 2002 the WQI rating at Boulder Creek at 61st St. (BC-61) was Good (B) due to a WQI value of 81.61. 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 132.10 83.91 0.17 14.26
Fecal Coliform #/100 mL 20.00 61.54 0.16 9.85
pH pH 8.32 76.89 0.11 8.46
Total Phosphate mg PO4/L 0.02 98.23 0.10 9.82
Nitrates mg NO3/L 0.10 97.90 0.10 9.79
Turbidity NTU 2.40 91.31 0.08 7.30
Total Solids mg/l 195.00 71.29 0.07 4.99
Totals (factors, total) 0.79 64.48
Adjusted WQI 81.61

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 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