CBP Water Quality Data (1984–present): Water quality, light attenuation, and optical density collected throughout the Chesapeake Bay watershed subdivided into three Chesapeake Bay Program (CBP) monitoring programs: Tidal Water Quality Monitoring, Shallow Water Monitoring, and Nontidal Water Quality Monitoring. See the CBP Water Quality Data Diagram for more information.

Historical CBI Water Quality Data (1949–1982): Physical parameters and nutrient data collected by the Chesapeake Bay Institute (CBI) of the Johns Hopkins University between 1949 and 1982.

Annual Water Quality Data Files: Download annual water quality data files organized by (1) data stream (e.g., traditional or nontraditional partnership) and (2) tidal influence: tidal (Tidal Water Quality Monitoring and Shallow Water Monitoring Programs) or nontidal (Nontidal Water Quality Monitoring Program). Contains physical and chemical parameter concentrations at specific depths within the water column.

• Hover over the help icon “?” for more information about each query option including program and project descriptions.
• Geographical attribute options are displayed based on the year range only; if no results appear, try adjusting the month and day values within your selected years.
• The Water Quality Data Lookup Tables Excel file provides additional information on the acronyms and codes used in all Water Quality datasets.
• Find metadata files, maps, and additional documentation at the Data Documentation page.