Patuxent is getting cleaner

December 04, 1990|By Timothy B. Wheeler | Timothy B. Wheeler,Evening Sun Staff

The effort to restore Chesapeake Bay still has a long way to go, but Maryland officials say they already see signs of recovery in the rivers that feed the ailing estuary.

New data from long-term monitoring indicate that the Patuxent River, one of the Chesapeake's major tributaries, is getting cleaner, according to scientists with the Maryland Department of the Environment.

In the past five years, there has been a dramatic drop in the river's levels of phosphorus, one of two nutrients blamed for choking off bay grasses and fish.

The phosphorus declines, which range from 25 percent near Lower Marlboro in Calvert County to 50 percent near Bowie, stem from the state's 1985 ban on phosphate detergents and from nearly $196 million being spent upgrading municipal sewage plants along the river.

State sampling of the Patuxent and three other large rivers also suggests that the bay cleanup campaign is beginning to curb the nutrient pollution washing off farm fields and suburban lawns during rainstorms.

State scientists are scheduled to present their latest readings on the bay's health at a three-day Chesapeake research conference beginning today in Baltimore. Scientists and officials plan a year-long re-evaluation of the 1987 bay pact's goal of reducing nutrient pollution by 40 percent by the end of the decade.

The Patuxent progress has "major implications" for the bay cleanup effort, said Robert Perciasepe, the state's incoming environment secretary. Maryland began cleaning up the river in 1982, two years before joining neighboring states and the federal government in trying to restore the Chesapeake.

"We're greatly encouraged that the state's strategy to restore the Patuxent is working," said Michael Haire, administrator of monitoring and research for the environment department. "It is especially good news since the bay-wide strategy evolved from our experiment."

The Patuxent's 900-square-mile drainage basin encompasses seven Maryland counties: Anne Arundel, Calvert, Charles, Howard, Montgomery, Prince George's and St. Mary's. It is the only major bay tributary that is entirely within the state.

Like the bay cleanup campaign, the Patuxent effort has focused on reducing nutrients, particularly phosphorus and nitrogen from sewage and storm runoff. Excess nutrients cause algae blooms, which deprive the water of the oxygen and light needed to keep fish and underwater grasses alive.

The effort has paid off, state scientists say. Phosphorus entering the river from eight major sewage plants has been reduced by more than 75 percent since 1981, despite a 33 percent growth in population in the river basin to 463,000 people this year, 'N according to Robert Magnien, chief of the state's bay monitoring.

Since 1985, when the phosphate detergent ban took effect, phosphorus levels have dropped by 50 percent in the river from the U.S. 50 bridge to Jug Bay in southern Anne Arundel County, Magnien said.

The impact diminishes farther downstream from the sewage plants, though phosphorus levels from Jug Bay almost to Benedict still are 25 percent below what they were five years ago, Magnien said.

Phosphorus declines have not been as large near the mouth of the river, said Magnien, and phosphorus levels overall have not declined enough to curb algae growth. Nor have underwater grasses returned to the Patuxent's bottom, which has been practically barren for years.

But the phosphorus reductions in the Patuxent suggest that the direction of the bay cleanup appears to be correct, officials say.

Levels of nitrogen, the other major nutrient affecting the bay, have not declined much so far. But state officials say they expect a major drop in nitrogen entering the Patuxent next year because of a $38 million upgrade of the Western Branch sewage plant, just finished.

The Patuxent is showing signs of recovery similar to those seen in the Potomac, where pollution cleanup efforts begun in the 1970s paid off with improved water clarity, fewer algae blooms and rebounding underwater grasses and fish stocks.

"I'd say five years from now, you'd be able to look back [at the Patuxent] and see similar kinds of trends," Magnien said.

Meanwhile, state monitoring of the Patuxent near Bowie has tracked an 8 percent decline in nitrogen washing off the land in rainstorms since 1984, said Robert Summers, chief of water quality restoration projects.

Such pollution has been hard to measure, much less reduce, because it comes from many different places along the river. The state's data are the first to look at runoff pollution independent of annual fluctuations in rainfall.

Nitrogen runoff into the Potomac, Choptank and Susquehanna rivers apparently has leveled off in the past six years, after growing 13 to 25 percent through the late 1970s and early 1980s, Summers said.

Meanwhile, phosphorus runoff to the Potomac has dropped dramatically, declining 44 percent since 1984. The Choptank has experienced a 20 percent reduction in phosphorus runoff, while the Susquehanna -- the major source of fresh water in the upper bay -- has shown no significant changes in phosphorus runoff in recent years.

The declines in phosphorus and leveling-off of nitrogen pollution from runoff are the result of improved pollution management for development and some farmland going out of production, Summers said.

But he warns that unless more effort is put into controlling the environmental impacts of growth, the progress made so far will be lost.

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