USGS Ohio Indiana Kentucky Water Science Center

Super Gage Network

Indiana Kentucky Water Science Center Surrogate Constituent Models

"Surrogate" Constituent Models are developed at USGS streamflow gages, called Super Gages, throughout Ohio, Kentucky, and Indiana. Each Super Gage deploys a variety of in-situ continuous water-quality monitors and is intermittently sampled for water-quality constituents over the range of hydrologic and seasonal conditions. By statistically combining continuous water-quality data with intermittent samples, models are developed to continuously estimate constituents that are not easily measured in real-time. For example, after a Surrogate Constituent Model is developed, turbidity (clarity of water) may be used to estimate suspended sediment concentration. Click here for a list of Ohio-Kentucky-Indiana Water Science Center Surrogate Constituent Models.

National Real-Time Water Quality

Many states provide hourly computed concentrations and loads for sediment, nutrients, bacteria, and many additional constituents; uncertainty values and probabilities for exceeding drinking water or recreational criteria; frequency distribution curves; and all historical hourly in-stream sensor measurements.

USGS National Real-Time Water-Quality Web Site

Ohio-Kentucky-Indiana Water Science Center regression models are listed in the table below. The list of these models also is available as a Microsoft Excel spreadsheet.

Data Sampled
Regression Model Explanatory
RMSE R2 n Bias
or smear
web sitec
Start End Start End
Yellow River near Oak Grove, IN (USGS Site ID: 05516665)
2012 2013 1-169 log10(SSC)=0.7856*log10(TURB)+0.5645 0.8-130 0.157 0.83 22 1.0632 2014 present 8/19/2014
Yellow River at Knox, IN (>USGS Site ID: 05517000)
2012 2013 14-1050 log10(SSC)=1.2269*log10(TURB)+0.0854 9.7-160 0.21 0.84 17 1.1146 2014 present 8/13/2014
Yellow River near Brems, IN (USGS Site ID: 05517010)
2012 2013 4-1150 log10(SSC)=0.745+(0.191*sqrt(TURB)) 0.3-150 0.18 0.91 27 1.083 2015 present 8/27/2014
White River at Hazleton, IN (USGS Site ID: 03374100)
2010 2011 16-434 log10(SSC)=0.968*log10(TURB)+0.330 9-170 0.08 0.96 13 1.015 2014 present 2/21/2012
Eagle Creek at Zionsville, IN (USGS Site ID: 03353200)
2010 2014 4-903 log10(SSC)=0.7837*log10(TURB)+0.6015 2-460 0.26 0.77 37 1.1722 2014 present 5/20/2015
Kankakee River at Davis, IN (USGS Site ID: 05515500)
2013 2015 1.2-130 SSC=14.362*sqrt(TURB)-8.662 7-161 8.74 0.94 20 NA 2016 present 03/7/2016

aConstituent and unit of measurement: suspended-sediment concentration (SSC) in milligrams per liter (mg/L).

bExplanatory Variables: Turbidity (TURB, YSI 6136).

cYears regression has been available on USGS National Real-Time Water-Quality (NRTQW) web site.

dModels listed followed protocols from Rasmussen, P.P., Gray, J.R., Glysson, G.D., and Ziegler, A.Z., 2009, Guidelines and Procedures for Computing Time-Series Suspended-Sediment Concentrations and Loads from In-Stream Turbidity-Sensor and Streamflow Data: U.S. Geological Survey Techniques and Methods book 3, chap. C4, 53 p.