The Bay's Problems

THE SUBURBS: The watershed's forests and bogs used to do a good job of trapping trash, pollution and sediment (floating dirt) before it reached the Chesapeake. But these green places are being replaced by houses and stores. More streets and parking lots result in more rainwater being fast-forwarded -- grit and all -- into storm drains, and eventually the bay.

Sediment blocks light, which kills the bay grasses where baby crabs, little fish and other animals live. The teens recall seeing one very brown, sediment-filled creek pouring into the clear waters of the Potomac. It was like "that chocolate river in the Willy Wonka movie," said Justin Powers, 17.

FARMERS: The paddlers saw hundreds of cows in the river that "would always leave us these lovely floating presents," said Brittany Casey, 16, referring to bobbing feces.

Animal waste contains nitrogen, a nutrient that makes plants grow. (Farmers' fertilizers also have nitrogen and other nutrients that end up in the bay.)

Nitrogen makes algae grow. Algae are scummy-looking microscopic plants. Rotting algae takes oxygen out of the water. That sickens and kills bay life.

Officials believe excess nutrients and sediment are the cause of fish lesions and huge fish kills, including one this spring that wiped out half of the smallmouth bass along an 80-mile stretch of the Shenandoah River.

CITIES: Cities also poison the Chesapeake. About 75 times each year, heavy rains in Washington cause the city's aging sewer system to overflow, pouring a total of about 3 billion gallons of raw sewage into the Anacostia River, and then the bay.

Sewage (waste you flush down the toilet) also contains nitrogen and harmful bacteria.

Cattle keep cool in, and pollute, the Potomac River basin.