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

Grade C For January, 2002 the WQI rating at Boulder Creek at 75th St (BC-75) was Medium (C) due to a WQI value of 60.95. 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 87.00 91.21 0.17 15.51
Fecal Coliform #/100 mL 20.00 61.54 0.16 9.85
pH pH 6.96 85.41 0.11 9.40
Total Phosphate mg PO4/L 2.13 23.23 0.10 2.32
Nitrates mg NO3/L 13.00 5.50 0.10 0.55
Turbidity NTU 1.50 93.93 0.08 7.51
Total Solids mg/l 412.00 43.06 0.07 3.01
Totals (factors, total) 0.79 48.15
Adjusted WQI 60.95

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

Return to WQI map for January


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