USGS Scientific Investigations Report 2010–5008 Use of Continuous Monitors and Autosamplers to Predict Unmeasured Water-Quality Constituents in Tributaries of the Tualatin River, Oregon

Table 7. Datasets showing laboratory sample results and summary statistics for scenarios used for calibration and validation of regression models with continuous monitors at Dairy Creek at Highway 8 near Hillsboro, Oregon.

[Discharge, turbidity, and specific conductance data were from records at stream gages and continuous monitors. Occasional Clean Water Services samples were collected at higher discharges than shown here, but continuous monitors were not installed at the time so samples could not be used for this study. Abbreviations: FNU, Formazin Nephelometric Unit; E. coli, Escherichia coli bacteria; n, number of samples (numbers for individual models may vary where missing values or outliers were removed); ft³/s, cubic foot per second; µS/cm, microsiemens per centimeter; mg/L, milligram per liter; No./100 mL, colony count per 100 milliliters]

Scenario and summary statistic	Calibration						Validation
Scenario and summary statistic	Discharge (ft³/s)	Turbidity (FNU)	Specific conductance (µS/cm)	Total suspended solids (mg/L)	Total phosphorus (mg/L)	E. coli (No. /100 mL)	Total suspended solids (mg/L)	Total phosphorus (mg/L)	E. coli (No. /100 mL)
Scenario 1	Autosampler (2002–03), n = 38						Clean Water Services ambient monitoring (2001–04), n = 116
Minimum	38.7	5.7	117.0	5.0	0.09	40	2.8	0.05	28
Maximum	158.7	30	141.0	31.0	0.23	950	38.0	0.29	1,800
Mean	90.6	14	127.9	13.3	0.14	331	11.9	0.12	286
Median	92.4	15	124.5	11.5	0.14	260	11.2	0.11	185
Standard deviation	34.7	6	7.2	6.7	0.04	256	5.4	0.04	302
Scenario 2	Autosampler peak discharge samples, Clean Water Services first monthly + high flow, n = 42						Autosampler non-peak discharge samples, Clean Water Services remaining monthly and non-high flow, n = 113
Minimum	16.0	3.2	67.0	2.8	0.06	28	2.8	0.05	31
Maximum	705.0	16.2	190.0	38.0	0.21	1,500	31.0	0.29	1,800
Mean	137.1	10.0	108.3	12.8	0.11	256	12.1	0.13	314
Median	74.8	9.6	102.0	12.4	0.11	110	11.2	0.13	225
Standard deviation	162.2	3.4	25.8	6.4	0.04	329	5.5	0.04	277