One of the deepest parts of the Chesapeake Bay is the best place to put some of the sediment dredged to maintain Baltimore’s shipping lanes, according to a draft environmental impact statement completed by the Army Corps of Engineers.

The Maryland Port Authority has proposed the placement of 18 million cubic yards of dredged material in an area just north of the Bay Bridge, known as Site 104, over the next nine years.

The Corps, which would be in charge of the dredging operation, completed a draft Environmental Impact Statement in February that concluded the project would not pose significant environmental damage.

“No other alternative provides the required placement capacity and comparable environmental and economic benefits,” the study said. The corps is taking comments on the plan until April 12.

Such “open water placement” has long been opposed by many watermen, environmentalists and resource agencies because of the potential impacts on water quality and living resources.

George O’Donnell, president of the Queen Anne’s County commissioners, told state lawmakers at a hearing earlier this year that the project will threaten several thousand acres of oyster bars because tides will spread the silt far beyond the deep trough in the middle of the Bay.

“This is not about the Port of Baltimore. This is about water quality. We put water quality first,” he said.

The Chesapeake Bay Foundation, in a recent letter to EPA Administrator Carol Browner, included Site 104 on a list of 10 projects in the region that federal agencies should use their authority to block. The foundation said the project could threaten fish, shellfish, plants and water clarity.

A 1996 Maryland task force report that examined long-term options for dealing with dredged material recommended that a mix of six sites be used to hold the roughly 108 million cubic yards of material expected to be dredged over the next 20 years.

Among the six sites was an unspecified “open water” placement site, to hold 18 million cubic yards of dredged material. The Maryland Port Authority later recommended Site 104, which is located a half mile north of the Bay Bridge, and a mile west of Kent Island.

The Corps’ EIS said Site 104 was the best of the more than 30 options examined for the 18 million cubic yards. The 1,800-acre site was previously used from 1924 through 1950 to hold an estimated 70 million cubic yards of dredged material.

The EIS said the site was preferred because, compared with other options, it would have a minimal effect on resources. It is deep enough — ranging from 40 to 70 feet — that it is usually depleted of oxygen during the summer, so many species are unable to live there.

Placement of material would be done in late fall, winter and early spring to minimize impacts to migrating fish, phytoplankton, finfish and shellfish spawning and other biological activity. No contaminated sediment from Baltimore Harbor would be placed at the site.

But blue crabs use the site to overwinter and will be buried by the operation, although the EIS said crab densities were low compared with other areas, and the losses “are not expected to impact the Baywide population.”

Also, the EIS said that in a “worst case scenario” as much as 17 percent of the material could be eroded from the site and be deposited in other parts of the Bay. Models were unable to predict where that material would move and therefore could not predict what their impact would be, the draft report said.

The EIS said that when viewed in the context of other ongoing restoration projects in the Bay, the use of Site 104 would result in “cumulative improvements” to the Chesapeake system.

Elsewhere, for example, dredged material is being used for such activities as the reconstruction of the nearly vanished Poplar Island, which will restore hundreds of acres of valuable wetland habitat in the Bay.

But “beneficial use” projects are expensive, in part because suitable sites are often far from the shipping lanes being dredged. The Poplar Island project costs $5 per cubic yard of dredged material, while open water placement costs only about $1 per cubic yard. Therefore, port officials have said their dredging plans need to use a mix of low-cost open water placement to balance the high-cost, beneficial use projects.

About 3.5 million cubic yards of material has to be dredged from the Bay each year to maintain shipping channels to Baltimore.

The draft Environmental Impact Statement is available on the Corps of Engineers Baltimore District web site at www.nab.usace.army.mil