Nutrients brought to the Chesapeake Bay from runoff promotes algae growth and can kill off other species.
Wet weather and a lot of melting snow from Virginia to New York have meant heavy spring runoff into the Bay this year. All the water is bringing a flood of nutrients and sediments into the Bay.
That makes the water muddy, limiting underwater plant growth that serves as a foundation for many other species.
Nutrients picked up from fertilizers on lawns and fields -- as well as from urban wastewater -- create giant algae plumes in the spring and summer, which can harm all kinds of aquatic life across vast stretches of the Bay.
Researchers say much of the improvement in the Bay's health observed over the past years can be linked to the weather. The Department of Natural Resources says the flow over the Conowingo Dam on March 12 was the highest since Tropical Storm Ivan in 2004, and more than six times average for the month.