City of Boulder/USGS Water Quality Monitoring
Water Quality Index for March, 2002 at
Boulder Creek at 75th St

Grade C For March, 2002 the WQI rating at Boulder Creek at 75th St (BC-75) was Medium (C) due to a WQI value of 63.03. 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 0.00 99.00 0.17 16.83
Fecal Coliform #/100 mL 20.00 61.54 0.16 9.85
pH pH 7.26 92.62 0.11 10.19
Total Phosphate mg PO4/L 3.08 17.74 0.10 1.77
Nitrates mg NO3/L 10.10 12.62 0.10 1.26
Turbidity NTU 3.17 89.51 0.08 7.16
Total Solids mg/l 441.00 39.03 0.07 2.73
Totals (factors, total) 0.79 49.79
Adjusted WQI 63.03

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 WW Plant

WQI at Downstream Station: Boulder Creek above Dry Creek

WQI for February at this station

WQI for April at this station

Return to WQI map for March


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Last Page Update - Saturday December 24, 2005