Explore resources here describing water-quality load and trend results for nontidal rivers of the Chesapeake Bay watershed.
The health of the Chesapeake Bay is largely driven by changes in streamflow and the amount of pollution it contains. Runoff in the Chesapeake Bay watershed carries pollutants, such as nutrients and sediments, to rivers and streams that drain to the Bay. Scientists use estimated streamflow entering the Chesapeake Bay to assess the health of the Bay and make ecological forecasts.
Loads and Trends
The Chesapeake Bay Nontidal Monitoring Program quantifies nutrient and sediment loads in the bay's nontidal rivers and estimates changes over time (trends) in sediment and nutrient loads.
What are the Objectives of the Chesapeake Bay Nontidal Monitoring Program?
Quantifying nutrient and sediment loads in the nontidal rivers of the Chesapeake Bay watershed, and estimating changes over time (trends) in these loads, are the two primary objectives of the Chesapeake Bay Nontidal Monitoring Program.
Loads are defined as the mass of nutrient or sediment passing a monitored location per unit time.
Estimates of change over time (trends) in sediment and nutrient loads are made in a manner that compensates for any concurrent trend(s) in stream discharge. Trends estimated in this manner can indicate changes in the watershed, such as the effects of best management practices, that cannot be attributed primarily to climatic fluctuation.
How the Program Works
- Monitoring data are collected by numerous agencies through the nontidal monitoring partnership.
- Results are updated on even-numbered water years for the network of water-quality monitoring stations distributed throughout the Chesapeake Bay watershed.
What Data and Related Information Are Available?
Methods, data, results, and result interpretations are available for:
- Nutrient and sediment loads and yields (per-acre loads).
- Trends in nutrient and sediment loads.
Many nontidal load and trend resources are available, including:
- Click here to access and download annual load data by year.
- Click here to access and download annual load data by month.
- Click here to access and download yields tables.
- Click here to access and download trends tables.
- View Chesapeake Bay nontidal network load and trend tables and maps
The nine river input monitoring stations:
View and download data, nutrient, and suspended-sediment load and trend results for the following nine major rivers, known collectively as the Nine River Input Monitoring Stations (RIM). CLICK HERE for the most recent summary of RIM results.
- Choptank River near Greensboro, Md, (01491000)
- Susquehanna River at Conowingo, Md. (01578310)
- Patuxent River near Bowie, Md. (01594440)
- Potomac River at Chain Bridge at Washington, D.C. (01646580)
- Rappahannock River near Fredericksburg, Va. (01668000)
- Pamunkey River near Hanover, Va. (01673000)
- Mattaponi River near Beulahville, Va. (01674500)
- James River at Cartersville, Va. (02035000)
- Appomattox River at Matoaca, Va. (02041650)
Estimated Streamflow Water-Quality Loads and Trends Maps, Tables, and Figures Partners
Nitrogen, phosphorus, and suspended-sediment loads, and changes in loads, in major rivers across the Chesapeake Bay watershed are calculated using Chesapeake Bay Nontidal Network (NTN) monitoring station data for the period 1985 through 2020. Nutrient and suspended-sediment loads and changes in loads were determined by applying a weighted regression approach. See map, data and archive links below.
Nutrient and Suspended Sediment Loads at Chesapeake Bay Nontidal Network Stations
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).
Trends in Flow-normalized Load at Chesapeake Bay Nontidal Network Stations
Nutrient and suspended-sediment concentrations and loads and flow-normalized concentrations and loads were estimated using a weighted regression approach called Weighted Regressions on Time, Discharge, and Season (WRTDS; Hirsch and others, 2010), which is included in the R (version 4.1.3) software package called EGRET - Exploration and Graphics for River Trends.
Full-Featured Interactive Data Analysis and Maps
Click here to explore the Nontidal Network Mapper Geonarrative, a powerful interactive resource providing user-driven access to nutrient and suspended-sediment load and trend results from the Chesapeake Bay Program's nontidal monitoring network.
Explore maps describing Chesapeake Bay nitrogen, phosphorous, and suspended sediment loads and trends. Each map below, when clicked, becomes a multi-map slideshow that may be viewed, expanded to full screen, and downloaded. Links to related estimated streamflow data and archived water quality load and trend data and maps are also provided.
Freshwater Flow into Chesapeake Bay
The health of the Chesapeake Bay is greatly affected by freshwater flow from rivers draining its watershed. The estimated annual-mean streamflow entering the Chesapeake Bay over the period of record has been calculated for each of the complete water years in the period of record, beginning in 1937. For the water year 2021, this value was 84,880 cubic feet per second.
Water Quality Loads and Trends Archive
A full compliment of archived water-quality load and trend results for the nontidal rivers of the Chesapeake Bay watershed is provided along with downloadable data at these links.
Archive (continued):
WQ Loads and Trends Map Slide-Show Index
Scroll down to view the Chesapeake Bay Water-Quality Loads and Trends Map Slide Shows below.
- Overview
Explore resources here describing water-quality load and trend results for nontidal rivers of the Chesapeake Bay watershed.
The health of the Chesapeake Bay is largely driven by changes in streamflow and the amount of pollution it contains. Runoff in the Chesapeake Bay watershed carries pollutants, such as nutrients and sediments, to rivers and streams that drain to the Bay. Scientists use estimated streamflow entering the Chesapeake Bay to assess the health of the Bay and make ecological forecasts.
Loads and Trends
The Chesapeake Bay Nontidal Monitoring Program quantifies nutrient and sediment loads in the bay's nontidal rivers and estimates changes over time (trends) in sediment and nutrient loads.
What are the Objectives of the Chesapeake Bay Nontidal Monitoring Program?
Quantifying nutrient and sediment loads in the nontidal rivers of the Chesapeake Bay watershed, and estimating changes over time (trends) in these loads, are the two primary objectives of the Chesapeake Bay Nontidal Monitoring Program.
Loads are defined as the mass of nutrient or sediment passing a monitored location per unit time.
Estimates of change over time (trends) in sediment and nutrient loads are made in a manner that compensates for any concurrent trend(s) in stream discharge. Trends estimated in this manner can indicate changes in the watershed, such as the effects of best management practices, that cannot be attributed primarily to climatic fluctuation.
How the Program Works
- Monitoring data are collected by numerous agencies through the nontidal monitoring partnership.
- Results are updated on even-numbered water years for the network of water-quality monitoring stations distributed throughout the Chesapeake Bay watershed.
What Data and Related Information Are Available?
Methods, data, results, and result interpretations are available for:
- Nutrient and sediment loads and yields (per-acre loads).
- Trends in nutrient and sediment loads.
Many nontidal load and trend resources are available, including:
- Click here to access and download annual load data by year.
- Click here to access and download annual load data by month.
- Click here to access and download yields tables.
- Click here to access and download trends tables.
- View Chesapeake Bay nontidal network load and trend tables and maps
The nine river input monitoring stations:
View and download data, nutrient, and suspended-sediment load and trend results for the following nine major rivers, known collectively as the Nine River Input Monitoring Stations (RIM). CLICK HERE for the most recent summary of RIM results.
- Choptank River near Greensboro, Md, (01491000)
- Susquehanna River at Conowingo, Md. (01578310)
- Patuxent River near Bowie, Md. (01594440)
- Potomac River at Chain Bridge at Washington, D.C. (01646580)
- Rappahannock River near Fredericksburg, Va. (01668000)
- Pamunkey River near Hanover, Va. (01673000)
- Mattaponi River near Beulahville, Va. (01674500)
- James River at Cartersville, Va. (02035000)
- Appomattox River at Matoaca, Va. (02041650)
Estimated Streamflow Water-Quality Loads and Trends Maps, Tables, and Figures Partners
- Data
Nitrogen, phosphorus, and suspended-sediment loads, and changes in loads, in major rivers across the Chesapeake Bay watershed are calculated using Chesapeake Bay Nontidal Network (NTN) monitoring station data for the period 1985 through 2020. Nutrient and suspended-sediment loads and changes in loads were determined by applying a weighted regression approach. See map, data and archive links below.
Nutrient and Suspended Sediment Loads at Chesapeake Bay Nontidal Network Stations
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).
Trends in Flow-normalized Load at Chesapeake Bay Nontidal Network Stations
Nutrient and suspended-sediment concentrations and loads and flow-normalized concentrations and loads were estimated using a weighted regression approach called Weighted Regressions on Time, Discharge, and Season (WRTDS; Hirsch and others, 2010), which is included in the R (version 4.1.3) software package called EGRET - Exploration and Graphics for River Trends.
Full-Featured Interactive Data Analysis and Maps
Click here to explore the Nontidal Network Mapper Geonarrative, a powerful interactive resource providing user-driven access to nutrient and suspended-sediment load and trend results from the Chesapeake Bay Program's nontidal monitoring network.
- Multimedia
Explore maps describing Chesapeake Bay nitrogen, phosphorous, and suspended sediment loads and trends. Each map below, when clicked, becomes a multi-map slideshow that may be viewed, expanded to full screen, and downloaded. Links to related estimated streamflow data and archived water quality load and trend data and maps are also provided.
Freshwater Flow into Chesapeake Bay
The health of the Chesapeake Bay is greatly affected by freshwater flow from rivers draining its watershed. The estimated annual-mean streamflow entering the Chesapeake Bay over the period of record has been calculated for each of the complete water years in the period of record, beginning in 1937. For the water year 2021, this value was 84,880 cubic feet per second.
Water Quality Loads and Trends Archive
A full compliment of archived water-quality load and trend results for the nontidal rivers of the Chesapeake Bay watershed is provided along with downloadable data at these links.
Archive (continued):
WQ Loads and Trends Map Slide-Show Index
Scroll down to view the Chesapeake Bay Water-Quality Loads and Trends Map Slide Shows below.
- Partners