Monthly Loads Table

Loads are provided individually for each parameter and station in a simple table format. 
Not all constituents are available for all sites.

Key to column headings:
STAID = USGS Station ID
PCODE = Parameter code:
P00600 = Total nitrogen (as N)
P00631 = Nitrate (as N)
P00665 = Total phosphorus (as P)
P00671 = Orthophosphorus (as P)
P80154 = Suspended sediment
Year = Calendar Year (January - December)
Month = Month
Q = Mean flow for all days in specified month in cubic feet per second (ft^3/s)
Conc = Mean concentration for all days in specified month from the WRTDS-K model, in milligrams per liter (mg/L)
Load = Monthly load from the WRTDS-K model, expressed as an average daily load in pounds per day (multiply by #days in month for monthly total load)
FNConc = Flow normalized mean concentration for all days in specified month from the WRTDS model, in mg/L
FNLoad = Flow normalized monthly load from the WRTDS model, expressed as an average daily load in pounds per day (multiply by #days in month for monthly total load)
START_YR = First water year of modeling period used to estimate load
END_YR = Last water year of modeling period used to estimate load

Nutrient and suspended-sediment concentrations and loads were estimated using a combination of a weighted regression approach called Weighted Regressions on Time, Discharge, and Season (WRTDS; Hirsch and others, 2010) and an autoregressive Kalman model utilizing the serial correlations from each WRTDS model (Zhang and Hirsch, 2019), both of which are included in the R (version 4.1.3) software package called EGRET - Exploration and Graphics for RivEr Trends (version 3.0.7; Hirsch and DeCicco, 2015). The application of WRTDS to generate the results provided in this table is documented in Chanat and others (2016).

Nutrient and suspended-sediment flow-normalized concentrations and loads were estimated using concentration and load estimates from the non-Kalman WRTDS model.

References Cited:

Hirsch, R.M., Moyer, D.L., and Archfield, S.A., 2010, Weighted regressions on time, discharge, and season (WRTDS), with an application to Chesapeake Bay river inputs: Journal of the American Water Resources Resources Association, v. 46, no. 5, p. 857-880

Zhang, Q. and Hirsch, R. M., 2019, River water-quality concentration and flux estimation can be improved by accounting for serial correlation through an autoregressive model: Water Resources Research, 55, 9705-9723. https://doi.org/10.1029/2019WR025338

Hirsch, R.M. and De Cicco, L.A., 2015, User guide to Exploration and Graphics for RivEr Trends (EGRET) and dataRetrieval: R packages for hydrologic data (version 2.0, February 2015): U.S. Geological Survey Techniques and Methods book 4, chap. A10, 93 p., http://dx.doi.org/10.3133/tm4A10 . (accessed May 24, 2016)

Chanat, J.G., Moyer, D.L., Blomquist, J.D., Hyer, K.E., and Langland, M.J., 2016, Application of a weighted regression model for reporting nutrient and sediment concentrations, fluxes, and trends in concentration and flux for the Chesapeake Bay Nontidal Water-Quality Monitoring Network, results through water year 2012: U.S. Geological Survey Scientific Investigations Report 2015-5133, 139 p. http://dx.doi.org/10.3133/sir20155133.

Select Station:
Select Parameter:
Select Year:
Columns default to ascending sort order going from left to right. To change the sort order, click the column name of the first column to sort, and then Ctrl-click each subsequent column to sort. Columns can be sorted ascending, descending, or not at all.
STAID PCODE Year Month Q Conc Load FNConc FNLoad START_YR END_YR