Problem Description

Our goal was to make the output from the Chesapeake Bay Water Quality model more accessible for common inquiries such as calculating the modeled hypoxic volume. This tool allows users to query the model results to calculate the volume of water with dissolved oxygen values less than certain cutoffs (e.g., 2 mg/L, 1 mg/L, or 0.2 mg/L) in a particular region of the Bay during a certain time period.
Data Used and Links/Documentation

Data: Dissolved oxygen concentration estimates for 1985-1994 from the 12,920 segment water quality model (CE-QUAL-ICM) of the Chesapeake Bay Environmental Model Package from the Army Corps of Engineers/Chesapeake Bay Program. The model grid covers the entire below fall-line regions of the Chesapeake Bay with a maximum of 20 depth layers.

Model documentation: On the EPA NSCEP site ( enter document number 903R04004 to download the 2002 documentation of the Chesapeake Bay Eutrophication Model.

Workflow Instructions

1. Beginning and ending dates: Select the appropriate dates for your time period of interest. The output will be generated for every day between your selected “begin” date and “end” date.

2. DO threshold (mg/L): Enter a dissolved oxygen concentration to use as the cutoff for defining hypoxia. Common hypoxic volume definitions include DO<1 mg/L or DO<2 mg/L. Anoxia is sometimes defined as DO<0.2 mg/L. Most DO values from the model output are between 0 and 12 mg/L.

3. Tributary: Select the location(s) in the Bay for your calculation. Note that some of the tributaries do not typically experience hypoxia.

4. View Report: Output will be generated in a table on the webpage. It may take a few minutes if you selected multiple years of output.

Output and Additional Options

Table: The table that is output to the webpage will include hypoxic volume (based on the user-set DO cutoff) in km3 and the percentage of the water volume in the region(s) selected that is hypoxic.

Downloads: Click “Select Format” to pick a file type for exporting the results. Then click “Export” to download the output to your computer.