Bay's nitrogen pollution rises to a 7-year high

Heavy rain flushed out pollutants left over from last year's drought

October 16, 2003|By Dennis O'Brien | Dennis O'Brien,SUN STAFF

The Chesapeake Bay Foundation said yesterday that levels of nitrogen, the bay's chief pollutant, are higher than they've been in seven years. And it's largely the result of the weather.

A report released yesterday estimates that 459 million pounds of nitrogen will flow into the bay this year, more than double the 201 million pounds reported last year. A total of 557 million pounds was recorded in 1972, the year of Tropical Storm Agnes.

Heavy rainfall this year -- more than 60 inches -- combined with a buildup of fertilizer left over from the previous year's drought -- sent larger-than-normal amounts of nitrogen and other nutrients flowing into the bay.

"The nutrients that would have been washed away in previous years didn't wash away, and they were just waiting on the watershed for this year's storms to come along," said William H. Street, director of watershed restoration for the foundation.

The report is based on monthly average water flows from eight U.S. Geological Survey river monitoring stations and sewer plant discharge reports required by state and federal environmental officials.

Street said the excessive nitrogen levels this summer increased the "dead zone" in the bay, an area unable to support aquatic life because of a lack of oxygen. Nitrogen and other nutrient runoff fuels algae blooms, which block sunlight and kill underwater vegetation that otherwise would produce oxygen.

When the algae die and decompose, bacteria that feed on them further deplete oxygen -- leading to dead zones.

This year's dead zone, measured each August, extended 50 miles farther than last year, reaching from the Back River in Baltimore County to the James River in Virginia, Street said.

Foundation officials said the report highlights the need to improve cleanup by upgrading sewage treatment plants, which are responsible for about 20 percent of the bay's nitrogen. Agricultural runoff contributes an additional 41 percent.

State and federal officials have set a goal of trimming nitrogen run off to 175 million pounds by 2010. "It means we have to move quickly on a variety of fronts," said John Surrick, a bay foundation spokesman.

Street said the nitrogen flow increases were widely anticipated by bay scientists because studies have established the relationship between droughts, heavy rains and nutrient runoff.

"It isn't a surprise," he said.

In the 12-month period that ended Sept. 30, more than 62 inches of rain fell at Baltimore-Washington International Airport, bringing an average daily flow of 76.2 billion gallons of fresh water into the bay.

Normal rainfall is about 42 inches, and the average daily flow of fresh water into the bay is about 50 billion gallons.

Records were set in 1972, when 78.1 billion gallons of water flowed each day into the bay and Tropical Storm Agnes dumped 9 inches of rain in the area.

Isabel, by contrast, produced about 3 inches of rain or less in Maryland this year.

This year's heavy rains also followed a severe drought. In the year ending Sept. 30, 2002, daily flows into the Chesapeake dropped to a scant 28.6 billion gallons.

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