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Past Projects and Resources

Integrated Trends Analysis Team

Tributary Summaries

The Chesapeake Bay Program and its partners produce tributary basin summary reports for the Bay’s 12 major tributaries using tidal monitoring data from more than 130 monitoring stations throughout the mainstem and tidal portions of the Bay. These reports use water quality sample data to summarize 1) How tidal water quality (TN, TP, DO, Chlorophyll a, Secchi Depth) has changed over time, 2) How and which factors may influence water quality change over time, and 3) Recent research connecting observed changes in aquatic conditions to its drivers.

These documents can be found on the CAST webpage here. 

Maps of 2020 Tidal Water Quality Change

  • Tidal Water Quality Change - 2020 (2.67 MB)

1. Long-Term Change

Observed change in water quality by station from the beginning of the period to 2020.

  • Surface Total Nitrogen, Annual 1985-2020 (462.47 KB)
  • Surface Total Phosphorus, Annual 1985-2020 (470.11 KB)
  • Surface Chlorophyll-a, Spring 1985-2020 (466.4 KB)
  • Surface Chlorophyll-a, Summer 1985-2020 (488.69 KB)
  • Secchi Depth, Annual 1985-2020 (449.67 KB)
  • Surface Total Suspended Solids, Annual 1999-2020 (444.54 KB)
  • Surface Water Temperature, Annual 1985-2020 (482.07 KB)
  • Bottom Dissolved Oxygen, Summer 1985-2020 (467.25 KB)

2. Long-Term Flow-Adjusted Change

Change in water quality by station computed under the condition of average freshwater flow into the Chesapeake Bay over the long-term.  This approach answers the question: “What would the change in water quality have been if flow had been average?”

  • Surface Total Nitrogen, Flow-Adjusted, Annual 1985-2020 (464.53 KB)
  • Surface Total Phosphorus, Flow-Adjusted, Annual 1985-2020 (463.86 KB)
  • Surface Chlorophyll-a, Flow-Adjusted, Spring 1985-2020 (453.73 KB)
  • Surface Chlorophyll-a, Flow-Adjusted, Summer 1985-2020 (464.17 KB)
  • Secchi Depth, Flow-Adjusted, Annual 1985-2020 (452.02 KB)
  • Surface Total Suspended Solids, Flow-Adjusted, Annual 1999-2020 (442.16 KB)
  • Surface Water Temperature, Flow-Adjusted, Annual 1985-2020 (485.2 KB)
  • Bottom Dissolved Oxygen, Flow-Adjusted, Summer 1985-2020 (476.98 KB)

3. Short-Term Change

Observed change in water quality by station over the last 10 years.

  • Surface Total Nitrogen, Annual 2010-2020 (409.42 KB)
  • Surface Total Phosphorus, Annual 2010-2020 (420.18 KB)
  • Surface Chlorophyll-a, Spring 2010-2020 (419.55 KB)
  • Surface Chlorophyll-a, Summer 2010-2020 (412.29 KB)
  • Secchi Depth, Annual 2010-2020 (411.76 KB)
  • Surface Total Suspended Solids, Annual 2010-2020 (435.74 KB)
  • Surface Water Temperature, Annual 2010-2020 (441.64 KB)
  • Bottom Dissolved Oxygen, Summer 2010-2020 (436.98 KB)

4. Short-Term Flow-Adjusted Change

Observed change in water quality computed under the condition of average freshwater flow into the Chesapeake Bay over the last 10 years.

  • Surface Total Nitrogen, Flow-Adjusted, Annual 2010-2020 (443.46 KB)
  • Surface Total Phosphorus, Flow-Adjusted, Annual 2010-2020 (416.5 KB)
  • Surface Chlorophyll-a, Flow-Adjusted, Spring 2010-2020 (418.88 KB)
  • Surface Chlorophyll-a, Flow-Adjusted, Summer 2010-2020 (419.39 KB)
  • Secchi Depth, Flow-Adjusted, Annual 2010-2020 (416.76 KB)
  • Surface Total Suspended Solids, Flow-Adjusted, Annual 2010-2020 (429.34 KB)
  • Surface Water Temperature, Flow-Adjusted, Annual 2010-2020 (455.21 KB)
  • Bottom Dissolved Oxygen, Flow-Adjusted, Summer 2010-2020 (456.19 KB)

Additional 2020 Results

Includes other depths and parameters not included in sections 1-4 above.

Bottom Layer (TN, TP, and Temperature)

Dissolved Nutrients

Surface Dissolved Oxygen

Please reach out to Alex Gunnerson (agunnerson@chesapeakebay.net) or Rebecca Murphy (rmurphy@chesapeakebay.net) for the 2019 results.

GAM Documentation

  • Draft-GAM Method for Chesapeake 5-10-18 (1.06 MB)
  • Appendix 1A Baytrends Quick Start Instructions (2.2 MB)
  • Appendix 2.1A example R Package Files (852.74 KB)
  • Appendix 2.3A - QW Data Format (164 KB)
  • Appendix 2.4A Ex GAM Models (690.32 KB)
  • Appendix 2.5A Percent Change (519.04 KB)
  • Appendix 2.6A Censored Data Approaches (618.3 KB)
  • Appendix 2.6B Summary of Censoring (582.23 KB)
  • Appendix 2.6C Censoring Scenarios (8.24 MB)
  • Appendix 2.7A Lab Change Approach (693.63 KB)
  • Appendix 2.8A Create Seasonally Detrended Flow and salinity Data sets (288 KB)

ITAT documents

  • Synthesis of Watershed Trends and Results - Jimmy Webber, John Clune, Alex Soroka (USGS) (15.57 MB)
  • Measuring and Explaining Trends in Water Quality - Jeni Keisman (240.31 KB)
  • Water Quality Criteria Attainment Patterns - Mindy Ehrich (3 MB)
  • GAM Development Briefing Oct 2015 - Rebecca Murphy (1.72 MB)
  • Monitoring Data in Support of Mid-Point Assessment - Doug Moyer, Joel Blomquist, Jeni Keisman (7.27 MB)
  • SK/GAM Comparison - Kyle Hinson (940.52 KB)

ITAT Web Publishing Policy

This document outlines the policies that the Integrated Trends Analysis Team will follow in publishing meeting presentation materials for a public audience.

  • Web Publishing Policy (91.3 KB)

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