Washington has cherry blossoms and Amsterdam has tulips, but springtime on the Rappahannock River is heralded by the appearance of a funkier-smelling species, a bony, scowling fish called shad.

While this rite of spring is less overt, with the shad hidden beneath the Rappahannock's coffee-colored waters, their arrival from salt water thousands of miles away is obvious to anyone in the Fredericksburg area, as fishermen appear on the riverbanks by the dozens, virtually overnight.

And there they stay, growing in number, from late March until mid-May, when spawning season ends. A staple in the economic and culinary life of Colonial America, shad are a springtime obsession for present-day fishermen in an area already crazy about fishing.

"It's a fever," said Dick Romagnoli, 69, smiling dreamily as he described how, for the next month or so, he'll come down to the river about sunset nearly every night, wade in and fly-fish for shad "until my arm aches," often past midnight. "You wait all year for this."

To the dismay of fishermen such as Romagnoli, the shad population has been dwindling for decades -- not only in the Rappahannock but around the Chesapeake Bay watershed -- a result of dams and overfishing, say state fisheries experts and environmentalists. But things are about to change on the Rappahannock.

A three-year process starts this summer to remove two dams on the Rappahannock near Fredericksburg. One is a small wood-and-stone "crib" dam built in the 1850s to divert water for drinking and agriculture. The other, the Embrey, is a larger concrete dam built in 1910 to generate electricity.

Part of a national trend, the dams' dismantling is expected to improve the habitat for migrating fish such as shad and herring. For more than a century, those fish have not had access to their historic spawning grounds upstream, which reach as far as Fauquier County.

Shad and herring populations have declined significantly in recent years in the Rappahannock, and larger local "resident" -- nonmigrating -- fish such as smallmouth bass are growing more slowly than they should because there are fewer of the smaller fish for them to eat, experts say.

Although the smaller Hickory shad are still plentiful in the Rappahannock, American shad have nearly vanished. Once the dams come down, state officials and environmental groups plan to stock the river upstream with American shad and plant underwater vegetation in an effort to return the Rappahannock to its more natural environment.

The trick will be luring the American shad back into waters its biological instincts may have forgotten.

The effect on the river is expected to be noticeable and comes as this region begins to wrestle with the consequences of a decade of explosive population growth and development. The area is in many ways becoming part of a massive exurb of Washington, 50 miles to the north, even as residents insist that that is their nightmare.

New state data indicate the first signs of water quality problems in the Rappahannock watershed, primarily because of water runoff from housing and commercial developments as well as animal waste and chemical runoff from farms, said John Tippett, executive director of Friends of the Rappahannock, a Fredericksburg-based nonprofit organization.

From its mouth at Chester Gap, in Rappahannock County, to its headwaters in the Chesapeake Bay, the Rappahannock is 184 miles long. However, the entire watershed includes hundreds of more miles of tributaries.

Compared with some rivers that feed the Chesapeake Bay, such as the heavily polluted Elizabeth River in Norfolk, the Rappahannock is relatively pristine, said John Kennedy, program manager for the Bay for the state Department of Environmental Quality. But when the state measures areas of the Bay watershed that have low levels of precious oxygen, much of that water is in the Rappahannock.

Oxygen-poor water is the result of nutrients -- nitrogen and phosphorous, for example -- running off streets, wastewater facilities and farms, getting into the water and creating algae, which eats up oxygen.

"I'd say, overall, the patient has been stabilized but still needs additional work," Kennedy said of the Rappahannock.

To shad fishermen, the health of the river is proven by the presence -- or absence -- of the fish. "If they're not there, there's a problem," says Smith Coleman, a fly-fishing guide, "because they always were."

Although fishing enthusiasts don't always champion the removal of dams -- which often create huge, beautiful, accessible lakes -- anglers along the Rappahannock supported the removal of Embrey -- which has deteriorated badly since it stopped producing electricity in the 1960s.

"Hopefully, it will open up 700 miles of spawning area," said Gordon Holloway, owner of the Fall Line, a Fredericksburg fly-fishing shop about a mile from the Rappahannock's fall line, the spot in a river where the tidal flow stops.

Best known on the East Coast, shad have a cult-like following among many fishermen for their ability put up a good fight as well as for their acrobatics. And then there's what Jay Nichols, of Fly Fisherman magazine, calls the "mystical" allure of salt-water fish that travel sometimes thousands of miles back to the fresh waters where they were born.

But shad season is particularly big in this area, attracting fishermen from Canada to Florida, in part because it's so easy to get to the Rappahannock's banks. The city owns about 20 miles of shoreline, which is undeveloped and public and much of which is reachable on foot. There are stretches of sandy beach -- including in downtown Fredericksburg -- that are perfect for fishermen in chest-high rubber waders. More common are rivers with rocky shores, deeper water and faster current.

In colonial times, people survived on shad, pickling it for winter and smoking it on wooden planks at public gatherings, "shad plankings," that were popular with politicians on the stump In a new book called "The Founding Fish," John McPhee writes that salt shad was a common provision for American troops in the 1700s, that Thomas Jefferson "liked his fresh shad laid open, broiled, and addressed with pepper, salt and butter," and that George Washington was a commercial shad fisherman.

Though a few hard-core residents still smoke shad on planks, most Rappahannock fishermen concede the fish is too bony and complicated to cook properly. Besides, it's illegal to keep American shad from the Rappahannock, and hickory shad can be kept legally only if it comes from certain spots.

However, restaurants often mark the annual shad run by cooking special dishes with the fish, or its roe, which is considered a delicacy.

"I have a standing order -- no matter how much it costs, when we see one bucket, I want it," said Christian Renault, owner and chef at La Petite Auberge, a restaurant in downtown Fredericksburg.

For several weeks, he has been serving shad roe cooked in bacon, with a little anchovy butter and parsley. He doesn't sell that much of it, and he admits to only eating shad roe himself once per year. But around here, shad is tradition.

"It's just one of those things," Renault said.

Fly-fishing guide Smith Coleman casts his line into the Rappahannock River during the annual shad spawning season, which runs from late March until mid-May.Coleman, left, instructs beginning fly-fisherman Doug Perkins, of Fredericksburg. Coleman sees the shad's decline as a worrisome sign of the river's overall health. "If they're not there, there's a problem," he says, "because they always were."The shad's appeal dates to colonial times. Fishermen say two dams have limited the fish's ability to swim up river. Right, Smith Coleman shows a favorite lure.