Calibration data and model archive summaries for suspended-sediment, total nitrogen, and total phosphorus concentration surrogate models in York County, Pennsylvania, 2019-2023 (ver. 2.0, May 2024)

The U.S. Geological Survey (USGS), in cooperation with the York County Planning Commission and York County Conservation District, has collected discrete stream samples for analysis of suspended-sediment, total nitrogen, and total phosphorus concentrations at six real-time streamflow and water-quality monitoring (turbidity, nitrate, and specific conductance) stations located in York County, Pennsylvania. Data were collected from 2019-2023 at these stations for the application of predicting suspended-sediment, total nitrogen, and total phosphorus concentrations using real-time continuous turbidity, nitrate, specific conductance, and streamflow. Regression equations were developed by relating discrete-sample suspended sediment and continuous turbidity, discrete sample total nitrogen and continuous nitrate plus nitrite (also referred to as NOx) and specific conductance, and total phosphorus and continuous turbidity data, and streamflow data. Regression equations included possible explanatory variables (independent variables) of continuous turbidity, continuous NOx, continuous specific conductance, 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, TP, and TN models include the variables of datetime (nearest 15-minutes), sample datetime (exact time of sample), suspended sediment, total phosphorus concentrations (in milligrams per liter, mg/L as P), total nitrogen concentrations (in milligrams per liter, mg/L s N), turbidity (in formazin nephelometric units, FNU), specific conductance (in microsiemens per centimeter at 25 degrees Celsius), NOx (nitrate plus nitrite, in mg/L as N), 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, turbidity, streamflow; natural log transformed variables of total nitrogen, NOx, specific conductance, and streamflow; and the calculated seasonal terms of JulianDay (Julian Day, integer representation of day of year), sin(2*pi*Julian Day/365), cos(2*pi*Julian Day/365), sin(4*pi*Julian Day/365), cos(4*pi*Julian Day/365), and sand (suspended-sediment particles classified as “sand”, 100 – fines, in percent).

Models were developed for 6 stream sites at or near these USGS stream gages:

01573660 Fishing Creek at Goldsboro, PA

01574000 West Conewago Creek near Manchester, PA

01575598 Codorus Creek near Saginaw, PA

01576007 Kreutz Creek at Strickler, PA

01576045 Fishing Creek at Craley, PA

01577500 Muddy Creek at Castle Fin, PA

Data sources for models:

For the models developed for station 01573660, discrete and continuous data are based on data from station 01573660.

For the models developed for station 01574000, discrete and continuous data are based on data from station 01574000.

For the models developed for station 01575598, discrete and continuous data are based on data from station 01575598.

For the models developed for station 01576007, discrete and continuous data are based on data from station 01576007.

For the models developed for station 01576045, discrete and continuous data are based on data from station 01576045.

For the models developed for station 01577500, discrete and continuous data are based on data from station 01577500.

First release: March 2024 (available from author)

Revised: May 2024 (ver. 2.0)