Learn the Issues

Learn about many of the complex problems facing the Chesapeake Bay, from the excess nutrients and sediment that pollute our waters, to the invasive species that crowd out native plants and animals, to a changing climate that is already affecting our land, air and water.

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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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

Development

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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Two streams connect: one of which is light brown due to sediment runoff.

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.

Wastewater

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?

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

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.

Groundwater

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.

Oysters

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.

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.

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

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.