Chesapeake Bay Program - A Watershed Partnership

Bay Pressures

The Chesapeake Bay and its many tributaries endure an array of assaults from the air, water and land. The watershed's worst problem is nutrient pollution, which fuels the growth of algae blooms that impact water quality and aquatic life. Chemical contaminants, air pollution, landscape changes, erosion and over-harvesting of fish and shellfish also stress the Bay and its wildlife.

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Land & People

Everything we do on the land—from driving our cars to spreading fertilizers on farms and suburban lawns—has an impact on the Bay and our local waterways.
Population Growth | Development | Impervious Surfaces | Stormwater | Land Use | Transportation

Air & Water Pollution

Nutrients, sediment and chemical contaminants that make their way to the Bay worsen water quality and stress aquatic life. Airborne nitrogen that falls onto the land can also add to pollution loads to local waterways.
Nutrients | Sediments | Chemical Contaminants | Air Pollution

Fisheries Harvest

The Bay and its tributaries provide rich grounds for commercial and recreational catches. Overfishing, pollution and disease now threaten many fish and shellfish.
Blue Crab Harvest | Oyster Harvest | American Shad Harvest | Atlantic Menhaden Harvest | Striped Bass Harvest

Natural Factors

There are many natural, uncontrollable pressures on the Bay. High temperatures, strong storms and inconsistent freshwater flows from rivers can all impact water quality and aquatic life.
Weather | River Flow | Groundwater

Invasive Species

Invasive species are non-native animals and plants that negatively affect their new ecosystem. Over 200 known or possible invasive species exist in the Bay region.
Mute Swan | Nutria | Phragmites | Purple Loosestrife | Water Chestnut | Zebra Mussel

Climate Change

Like countless other parts of the world, the Chesapeake has begun to feel some of the effects of a changing climate, such as sea level rise and increased temperatures. Other possible impacts may include lower dissolved oxygen levels, more precipitation, and changes in some species’ abundance and migration patterns.

Bay Pressures Assessment:

Pressures on the Bay ecosystem, as assessed in March 2008:

• Natural Factors: Total river flow to the Bay during the 2007 water year (October 2006-September 2007) was very close to the long-term average despite several months of extremes. Climate change and variability have caused water temperatures in the Bay to exhibit greater extremes during the 20th century than the previous 2,000 years. Sea-level rise related to climate change is contributing to the loss of vital coastal wetlands.
• Pollutants: Pollutant loads continue to exceed target levels established to restore the Bay’s water quality.
• Land Use: The human population in the Bay watershed is now growing by about 130,000 residents annually. The cumulative impact of centuries of population growth (currently nearly 17 million) and landscape changes has taken its toll.
• Fisheries Harvest and Pressures: Historic over-harvest, compounded by the impacts of poor water quality, disease and blocked access to historic spawning grounds, has resulted in low abundances of oysters, crabs and shad.

To learn more about Bay pressures, visit our factors impacting Bay health assessment section.