Calibration data and model archive summaries for suspended-sediment, total nitrogen, and total phosphorus concentration surrogate models at USGS station 01575900, Chiques Creek near Marietta, Pennsylvania, 2021-2023

The U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Agriculture Natural Resources Conservation Service (USDA NRCS) has collected discrete stream samples for analysis of suspended-sediment, total nitrogen, and total phosphorus at the real-time streamflow and water-quality monitoring (turbidity and nitrate) station 01575900, Chiques Creek Near Marietta, Pennsylvania. Data were collected from 2021-2023 at this station for the application of predicting suspended-sediment, total nitrogen, and total phosphorus concentrations using real-time continuous turbidity, nitrate, and streamflow. Regression equations via Ordinary Least Squares were developed by relating discrete sample suspended-sediment concentrations and continuous turbidity, discrete sample total nitrogen concentrations and continuous nitrate plus nitrite, and total phosphorus concentrations and continuous turbidity data, and streamflow data. Regression equations include possible explanatory variables (independent variables) of continuous turbidity, continuous nitrate, streamflow, and calculated seasonal terms; and the response variables (dependent variables) of suspended-sediment, total nitrogen, and total phosphorus concentration using base-10 logarithmic (log10) or natural log (ln) transformations as appropriate on both the discrete and continuous data. Data files in .csv format for SSC, TN, and TP models include the variables of datetime (nearest 15-minute in-stream measurements), sample datetime (exact time of sample), suspended-sediment, and total phosphorus concentrations (in milligrams per liter, mg/L), turbidity (in formazin nephelometric units, FNU), streamflow (Q, cubic feet per second, cfs), suspended-sediment particles classified as “fine” (smaller than 0.0625 millimeters, in percent), the log base 10 transformed variables of suspended-sediment and phosphorus concentrations, log-10 turbidity, log-10 streamflow, and the calculated seasonal terms of JulianDay (Julian Day, integer representation of day of year), sin(2*pi*Julian Day/365), and cos(2*pi*Julian Day/365), and sand (suspended-sediment particles classified as “sand”, 100 – fines, in percent).

Data sources for models: For the models developed for station 01575900, discrete and continuous data are based on data from station 01575900.