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Causes of the Problems

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The Chesapeake Bay and its many tributaries endure an array of assaults from our actions in the air, water and land. The watershed’s worst problem is nutrient pollution, specifically too much nitrogen and phosphorus from fertilizers, waste water and vehicle emissions, that fuels unnaturally high algae growth in the water. Algae become so abundant that the color of the water turns brownish or greenish, blocking sunlight from reaching important underwater grasses. Eventually the algae die and are decomposed by bacteria that consume the oxygen needed by other aquatic creatures in the bay. Without enough oxygen dissolved in the water, aquatic creatures like fish, blue crabs and oysters become stressed or even die.

Landscape changes, erosion, chemical contaminants and air pollution also stress the Chesapeake Bay and its wildlife. Excess sediments – dirt, clay, silt and sand – hurt the Bay’s water quality by blocking the sunlight needed by underwater plants and grasses. Landscape changes, like development of forests and farmland, increase nutrient and sediment pollution into the Chesapeake Bay. As we lose forestlands, we permanently lose the Bay’s natural air and water filters, wildlife habitat and other significant functions that forests provide. As trees and plants are removed during development, construction sites can contribute 10 to 20 times more sediment pollution per acre than farmlands.

The Chesapeake Bay Program has also approved a supplemental indicator for measuring wastewater pollution that looks at average annual progress toward the 2025 planning targets by controlling for annual weather variations.

To learn more about pollution sources in your region, click on the image to the right, select a pollutant category and click on the map to see how much pollution enters your local river. The information in the charts is from the Chesapeake Bay Program Phase 5.3 Watershed Model.