Chesapeake Bay GIS: Agricultural Runoff

1. Chesapeake Bay GIS: Agricultural Runoff By: Joe Hunter & Emily Vontsolos

3. Watershed Data • Covers more than 64,000 square miles • Encompasses six different states • Land to water ratio is 14:1 • Contains more than 100,000 streams and rivers, making the Bay more vulnerable to harmful runoff

4. Agricultural Data: • Approximately 9 million acres of the watershed are devoted to farming. • Farming practices often include the use of inorganic fertilizers. • The impervious land adjacent to the Chesapeake Bay has major consequences. • Runoff from the watershed’s farmland (which often contains inorganic fertilizers) can easily enter the Bay through these impervious areas.

5. Inorganic Fertilizers contain nutrients, primarily phosphorous and nitrogen. • Since many tributaries flow near actively farmed land, inorganic fertilizer runoff tends to be present in the streams and eventually the bay. • These fertilizers, once in the waters, also favor algae growth and can cause algae blooms. • The danger of inorganic fertilizers in the bay are magnified by the Bay’s shallow waters

6. The shallow waters in the Bay inhibit the Bay’s flushing abilities. Therefore, nutrients are trapped in the Bay, which encourages cultural eutrophication and in turn decreases dissolved oxygen concentrations.

7. When cultural eutrophication occurs, algae populations explode. Once the algae has exhausted all their nutrients, the population declines, leaving large amounts of dead organic matter in the water. • The dead algae matter is decomposed by oxygen demanding bacteria. The bacteria’s activities can deplete oxygen concentrations in the water, which can devastate fish populations. This cycle has occurred in the Chesapeake Bay.

8. These graphs of predicted Phosphorous and Nitrogen show (with the downward purple triangles) that these levels will be decreasing in the future in most areas of the watershed. There are, however, two areas where red triangles show that the concentrations will be increasing and could continue to pollute the Bay. While these areas should continue to be watched, the large amount of purple triangles show hope for the Chesapeake Bay. A brighter future with less eutrophication and more dissolved oxygen in the Bay would be an environmental success.

9. Bibliography • http://www.chesapeakebay.net/content/maps/cbp_17024.pdf • http://www.chesapeakebay.net/Components/MakeThumb.cbpo?file=f:\inetpub\wwwroot\content\maps\cbp_16566.jpg&size=600 • http://www.chesapeakebay.net/Components/MakeThumb.cbpo?file=f:\inetpub\wwwroot\content\maps\cbp_19097.jpg&size=600 • http://www.chesapeakebay.net/content/maps/cbp_20178.pdf • http://www.chesapeakebay.net/content/maps/cbp_19208.pdf • https://www.e-education.psu.edu/earth540/content/c5_p5.html • http://www.umces.edu/summer2008.html • http://www.npr.org/templates/story/story.php?storyId=121588652 • http://www.chesapeakebay.net/status_flowadjustedphosphorus.aspx?menuitem=50309 • http://www.chesapeakebay.net/status_flowadjustednitrogen.aspx