Threats to the Bay

Agricultural Runoff

Farms provide us with food and fiber, natural areas and environmental benefits. But agriculture is also the largest source of nutrient and sediment pollution entering the Bay.

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Farm field with blue sky.

Air Pollution

Pollution emitted by cars, trucks, power plants and other sources doesn’t just cloud the air we breathe—it falls back onto the earth’s surface, where it can wind up in our waterways.

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Two smokestacks releasing emissions.

Chemical Contaminants

Almost three-quarters of the Bay’s tidal waters are impaired by pesticides, pharmaceuticals, metals and other chemicals, which can harm the health of both humans and wildlife.

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Chemicals are seen in the water.

Climate Change

Some effects of climate change—rising seas, warming water temperatures and prolonged periods of extreme weather—are already being observed in the Bay region.

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Flooding shows water rising up to the top of a park bench.

Conowingo Dam

The reservoir behind Conowingo Dam has long captured sediment flowing downstream, but recent studies have drawn attention to its changing effectiveness as a “pollution gate.”

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Water rushes out from one side of the Conowingo Dam


As more people move into the Chesapeake Bay region, development has turned forests, farms and other landscapes into subdivisions, shopping centers and parking lots.

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Concrete barriers placed in a waterway.

Fish Blockages

Removing dams or installing fish lifts allows migratory fish to return to upstream habitats and lets resident fish move freely throughout the region's rivers.

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A bridge allows water to pass underneath without impact fish travel.

Invasive Species

Invasive species—plants or animals that have been introduced to their current habitat—can cause harm when they establish themselves at the expense of native plants and animals.

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Large blue catfish

Nutrient Runoff

Plants and animals need nutrients to survive. But when too many nutrients enter waterways, they fuel the growth of algae blooms and create conditions that are harmful to underwater life.

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Algae growth is seen in a polluted stream.

Population Growth

Each of the 18.4 million people that live in the region affects the Bay: consuming resources, altering the landscape and polluting the air and water.

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Aerial view of Baltimore City.

Sediment Runoff

Sand, silt and clay are a natural part of the Chesapeake Bay. But in excess amounts, sediment can cloud the waters of the Bay and its tributaries, harming underwater life.

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A significantly dried up bank where sediment runoff comes from.

Stormwater Runoff

When precipitation falls on roads, streets, rooftops and sidewalks, it can push harmful pollutants like fertilizer, pet waste, chemical contaminants and litter into the nearest waterway.

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Storm drain sends water into a road, which will lead to the Bay.

The Dead Zone

When nutrient-fueled algae blooms die and decompose, the resulting low-oxygen conditions—known as “dead zones”—can suffocate underwater life and shrink available habitat.

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Dead fish wash up on a beach.


Hundreds of wastewater treatment facilities throughout the Chesapeake Bay region are being upgraded to reduce the amount of nutrients flowing into local waterways.

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Wastewater management building.

What's at Risk?

Bald Eagles

After widespread pesticide use devastated the region's bald eagle population, a ban on DDT and the active management of eagle habitat helped the region become home to one of the nation's highest concentrations of these iconic birds.

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Bald eagle soaring.

Blue Crabs

The Bay’s signature crustacean supports important commercial and recreational fisheries. But pollution, habitat loss and harvest pressures threaten blue crab abundance.

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Chesapeake Bay blue crab

Environmental Justice

Environmental hazards such as extreme heat and poor water quality adversely effect low-income communities and people of color.

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Forest Health

Forests are critical to the health of the Chesapeake Bay—but human activities have altered the region’s forests, reducing tree cover and fragmenting forests that still exist.

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Close up of leaves in a healthy forrest.


Drops of rain or snow that fall onto the land can seep through the soil and into groundwater, which can become contaminated when pollutants on land seep underground.

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Photo of slightly polluted water that will be absorbed by the ground below.


These small fish form an important link in the Chesapeake Bay food web, which is why fisheries managers have placed a cap on the amount of menhaden that can be harvested from the Bay.

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Hand holds a menhaden, about an inch long.


These raptors may be found on nearly every corner of the world, but the Chesapeake region is home to the largest concentration of nesting osprey.

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Osprey brings a stick back to its nest.


This iconic bivalve helps to improve water quality and provides food and habitat to other animals. But over-harvesting, disease and habitat loss have led to a severe drop in population.

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A pile of oyster shells.

Rivers and Streams

Hundreds of thousands of creeks, streams and rivers flow through the Chesapeake Bay region, sending fresh water to the Bay and providing habitat to aquatic plants and animals.

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A wide river lined by forest.


Once the most valuable finfish fishery in the region, pollution, historic overfishing and the construction of dams that block migration have lowered shad populations.

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School of shad are seen underwater

Stream Buffers

Streamside trees and shrubs prevent pollution from entering waterways, stabilize stream banks, provide food and habitat to wildlife and keep streams cool during hot weather.

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Photo of trees lining a river.

Striped Bass

Also known as rockfish, striped bass are recovering from a severe decline in the 1970s and 80s with the help of fishery management practices and Chesapeake Bay restoration.

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Man releases a striped bass after catching it.

Underwater Grasses

Underwater grasses grow in the shallow waters of the Bay and its streams. They provide food and habitat to wildlife, add oxygen to the water and trap sediment and nutrient pollution.

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Underwater grass shown.


Wetlands are critical in supporting the healthy waters and diverse wildlife of the region. But development, invasive species and sea level rise threaten these important areas.

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A blue heron standing in a shallow pool surrounded by reeds, grasses and low bushes.