The Patuxent River, the largest Chesapeake Bay tributary entirely within Maryland, is showing its first signs of new life after more than a decade of costly efforts to reverse its decline, state officials say.
Nutrient pollution fouling the river has been curtailed significantly in the past two years, thanks largely to more than $190 million spent upgrading eight major wastewater-treatment plants in Anne Arundel, Howard, Prince George's and Montgomery counties.
And downriver from those plants, scientists under contract to the Maryland Department of the Environment recently detected a "moderate" increase in the worms, tiny clams and other crustaceans that live in the mud at the bottom of the river near Jug Bay in southern Anne Arundel.
Though far from dramatic, the river's response offers hope for the bay, since in many ways the Patuxent has been a leading indicator for the much more ambitious multistate effort to restore the rest of the Chesapeake. Efforts to clean up the Patuxent began in 1981, two years before the bay states agreed to work together.
The state's findings, to be reported today at a research conference in Hilton Head, S.C., cheered state Sen. Bernie Fowler, the river's longtime champion.
"While I'm not going to jump up and down in any jubilance, I do feel a whole lot better about the health of the Patuxent River," said Mr. Fowler, a Democrat representing Southern Maryland. "But we've still got a long way to go."
The river, which meanders 110 miles through the rapidly growing Baltimore-Washington metropolitan area, is plagued by harmful algae blooms and is murky with mud washed off farm fields and developments.
Except for a few patches, the river is virtually barren of the underwater grasses that once lined its banks. Oysters, clams and some pollution-sensitive fish remain scarce.
The findings of new life on the river bottom are preliminary and limited to one small stretch of the river. But they show that the bay restoration effort is working, said David A. C. Carroll, state environment secretary. Those bottom-dwelling animals provide food for fish, he said, and their growth demonstrates that the river will recover its vitality if water quality is improved.
"It will be a long time before we see lots of grasses," Mr. Carroll said. But the increase in bottom-dwelling animals suggests that the river's "food chain is re-establishing itself."
Nutrient pollution has drastically upset the Patuxent's ecological balance, as it has that of the bay. Nutrients in wastewater, in farm and suburban runoff and in "fallout" from air pollution kill underwater grasses and feed massive algae blooms, which ultimately deplete the oxygen in water that fish need to breathe.
The cornerstone of the bay restoration effort is a pledge by Maryland, Pennsylvania, Virginia and the District of Columbia to reduce that nutrient pollution 40 percent by the end of the decade.
The levels of one major nutrient -- phosphorus -- have declined 16 percent bay-wide since 1984 because of improved sewage treatment, runoff controls and a ban on phosphate detergents. But concentrations of nitrogen, a more widespread nutrient, have remained essentially unchanged.
Yet in the Patuxent, nutrient levels have declined dramatically. In the past two years, nitrogen levels from around Bowie to Lower Marlboro have dropped 30 percent to 40 percent, said Dr. Robert Magnien, chief of Chesapeake Bay and special projects for the Maryland Department of the Environment. The river is the first bay tributary to show major reductions in that nutrient.
Most of the improvement stems from installation in the past few years of nitrogen-removal equipment at seven major wastewater treatment plants. An eighth plant, on the Little Patuxent River in Anne Arundel County, is due for a similar upgrade next year that will cost $3.5 million. Several plants use a new "biological nutrient removal" process, in which bacteria convert nitrates in wastewater to harmless nitrogen gas that escapes into the air.
Sewage treatment improvements also have reduced phosphorus levels throughout the river -- by as much as 70 percent near Bowie.
Dr. Magnien said it will take several more years before water quality improves much on the lower Patuxent, because nutrients from past pollution are seeping from bottom sediment there.