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Water-Quality Loads and Trends at Nontidal Monitoring Stations in the Chesapeake Bay Watershed

Summary of Trends Measured at the Chesapeake Bay Tributary Sites: Water Year 2013 Update

Prepared by the U.S. Geological Survey, December 5, 2014

The U.S. Geological Survey (USGS) works with partners in the Chesapeake Bay Program (CBP) to operate the Nontidal water-quality monitoring network. This network is designed to measure changes in nutrients and sediment in the Chesapeake Bay watershed. The nutrient and sediment data are updated and interpreted each year. This update for water-year 2013 focuses on nine river monitoring stations collectively known as the River Input Monitoring Program, or RIM. Updates for additional sites are available for 2012 and will be done again for the period ending in 2014.

Because the goals of Bay restoration efforts are to reduce nitrogen, phosphorus and sediment reaching the Bay, downward trends in concentration are considered improving conditions, while increasing trends are considered degrading conditions. The major findings for nutrient and sediment concentration trends for nine tributaries to Chesapeake Bay through 2013 are presented for two periods:

  • Long-term trends in concentrations (1985-2013)
  • Short-term trends in concentrations (2003-2013)

Total Nitrogen

  • Long-term Trends in total Nitrogen concentration are improving at five of nine sites including the three largest rivers tributaries - The Susquehanna, Potomac and James. Degrading conditions are observed at two sites since 1985.
  • Recent Short-term Trends in total nitrogen show only three sites with improving conditions and one site with degrading conditions. Changes at other monitoring sites were not detectable using standard methods.

Total Phosphorus

  • Long-term Trends in total phosphorus concentration are improving at three sites and degrading at three sites. The Susquehanna River showed no detectable change over the 29-year period.
  • Two of the nine monitoring sites showed degrading conditions over the more Recent Short-term Period for total phosphorus. Data from all other sites indicated no significant change.

Suspended Sediment

  • Long-term Trends in suspended sediment concentration are improving at three sites and degrading at one site. The Susquehanna River showed no detectable change over the 29-year period.
  • Degrading conditions for suspended sediment were observed at four of nine sites over the Recent Short-term Period. All other sites showed no significant change.

Table 1. Summary of long-term and short-term trends in flow-adjusted concentration for the River-Input stations.

trends summary table1

Additional Information:

  • Maps of the flow-adjusted concentration results are available as:
  • Tabular results for each station are available in the "Download" section of the navigation menu on this web site.
  • A summary of loads at the river-input stations is also on the 2013 Loads Summary Page.
The USGS also developed a new technique to compute flow-normalized loads. Results from this technique are planned in future updates. For more information go to:


Joel Blomquist, Baltimore MD,
Doug Moyer, Richmond, VA,
Ken Hyer, Richmond, VA,
Mike Langland, New Cumberland, PA,

For more information on USGS Chesapeake Bay Studies, contact Scott Phillips, or visit

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