FREDERICKSBURG, Va. - When the Army sets off explosives that punch a 100-foot hole in a concrete dam today, it will be more a cause for celebration than concern.
The detonation of 650 pounds of explosives will shake the ground and rattle windows. But it also will destroy a large portion of Embrey Dam, restore the scenic Rappahannock River to its natural state and give a boost to one of the East Coast's most prized fish - the American shad.
The $10 million project is being carried out by the Army Corps of Engineers - historically known for obstructing rivers. But the dam removal is part of an environmental strategy - nationally and in the Chesapeake Bay watershed - to create healthier fish habitats by restoring the natural flow of rivers.
The Army has code-named the operation "Noah Shiva," after the biblical figure associated with flooding and the Hindu goddess empowered with giving new life.
Since the 1980s, conservation groups have been working to bring down dams and put up fish ladders or lifts over those that remain. Nationally, an estimated 600 dams have been removed in recent years. Many, built as hydroelectric power sources, have become outdated and face regulatory reviews that could require fish passages, according to American Rivers, an environmental group.
Most of those removed have been much smaller than Embrey Dam, which is 770 feet long and 22 feet high. But Embrey is also outdated. Built in 1910, it was last used to generate power in the 1960s and is widely seen as little more than an obstacle in the river.
"The dam's getting old, it isn't used for anything, and we didn't want it falling down at the wrong time," says Fredericksburg Mayor William Beck.
Beck and others say the Embrey Dam project has widespread support here because it will help bring back the shad.
Shad, known for their bony but tasty flesh, became casualties of overfishing and a proliferation of dams over the past century that blocked them from spawning grounds. They spend most of their lives at sea but return to fresh water in the spring.
Until dams were built, the fish could swim 12,000 miles in an average life span, traveling from fall feeding grounds in the Gulf of Maine off New England to Binghamton, N.Y., more than 300 miles upriver from the bay. They were once so plentiful that farmers used them as fertilizer. But by the time Maryland imposed a catch moratorium in 1980, they had almost vanished.
Today, the bay's shad are rebounding, in large part because of a determined campaign to clear away dams and other obstructions to their historic spawning runs.
Experts say dam removals not only clear migratory routes for fish, but also replace still ponds with swiftly moving water, creating a much cleaner habitat. Removing dams in Maine and in Western states has meant the return of salmon, another prized fish suffering from loss of spawning habitat, environmentalists say.
"I think shad are going to come back as a major sports fish," says Michael Fritz, living-resources coordinator for the EPA's Chesapeake Bay Program.
Fritz says the Embrey dam project fits a pattern for the Chesapeake Bay watershed, where over the past decade some 1,350 miles of waterways have been cleared of dams and other obstructions. Most dams have been removed with backhoes, though - making the project on the Rappahannock the first of its kind.
John Tippett, executive director of the Friends of the Rappahannock, says that removing the Embrey would open up 700 miles of the river and its tributaries to shad and other migratory fish, such as the blueback herring and the American eel.
"You could safely say there's two decades of advocacy behind this," says Tippett, who is credited with persuading Virginia Sen. John W. Warner to back the project during a 1996 canoe trip.
The project also has the backing of many in this town of 20,000, perhaps best known for its Civil War historic sites and antiques shops and, increasingly, as a Washington suburb.
The river frames the town's northern border, and the dam is part of its history.
Images of it abound: Beck's antiques shop has a map in the window showing where restricted areas and viewing stands will be set up.
In City Hall, a photograph of the dam decorates the coffee mug used by David King, a city engineer. In the lobby, a wooden block plucked out of the river, part of a 19th-century "crib" dam built 60 years before Embrey, is on display.
Few here are mourning the dam's demise. Since it stopped generating power, Embrey has been little more than an attraction - and a hazard - for sightseers and schoolchildren. No one seems worried about damages from the blast.
"They wouldn't be doing it if they thought it was a danger to anything," says Andy Callander, 22, a waiter, who fished near the dam as a teen-ager.
Crowds at the noontime blast today will be kept 1,000 yards from the explosion site. The 100-foot hole being created is on the south side of the river near Fredericksburg. City officials have urged residents to keep pets at home and promised to provide ear plugs.
Water is expected to rise - temporarily - only 2 to 3 feet, flooding little more than a few riverbanks and a deserted island downstream.
A pair of Army scientists predict no damage to the few houses that lie within 1,000 yards of the blast site, says Brian Rheinhart, the corp's project manager.
He says the explosive will be set off in a series of 10 shots, sequentially fired 25 milliseconds apart - quick enough to sound like one big blast. The charges will be planted inside holes carved into 10 concrete supports or "bays" by divers and demolition experts from Nellis Air Force Base in Nevada and the Army's Fort Eustis, Va.
Rheinhart says the explosives may not completely bring down the 100-foot portion of the dam where they are planted - an upper panel of concrete may remain stretched over the damaged structure. But the blast will punch a hole large enough to let the water and fish begin to flow through, he says.
Boaters will be kept out of the area while debris is cleared, a project that won't be completed until early 2006, Rheinhart says.
Late last week, city officials were searching for an old-fashioned dynamite plunger for Warner to use to set off the explosions.
Tippett expects shad to begin reappearing in the Rappahannock as early as this spring. Volunteers began releasing them into the Rappahannock with the help of Virginia game officials about four years ago, he says.
"I was out there for that. It was a lot of fun," says Ron Woodson, a Rappahannock River guide and helicopter mechanic at Fort Belvoir, Va. Woodson, in a brief tour of the Rappahannock last week, says he is confident the shad will return. Fish have returned to other rivers where dams have been removed, he notes.
"I think it's going to improve fishing a lot," he says.