Waterman Rocky Rice

Waterman Rocky Rice uses hand tongs to dredge the bottom of the Potomac river near a proposed development site on which a developer wants to build a 143 slip marina, hotel, conference center, etc., on the shore of what was once a significant oyster bar on the Potomac river. (Barbara Haddock Taylor / Baltimore Sun / April 28, 2014)

— With oysters showing signs of revival in the Chesapeake Bay, some are trying to bring the bivalves back in the bay's second largest tributary, the Potomac River.

Just two years into their fledgling effort to restore the river's once-bountiful oyster population, however, organizers are raising alarms about a large marina proposed in Charles County near the Potomac's largest and formerly most productive oyster bar.

The 143-slip marina would provide berths for residents and guests of a 900-acre resort community planned on the waterfront here. The development is planned to include 1,500 homes and a conference hotel.

"If this gets through the Board of Public Works and they build this marina, I don't see how we can go in and spend money planting oysters," said Martin L. Gary, executive secretary of the Potomac River Fisheries Commission. "We're going to lose this bar."

The land-side development, years in the planning, already has all necessary approvals, including a "growth allocation" from Charles County that exempts it from some waterfront development restrictions generally required under Maryland's Critical Areas law. The marina also received a green light in 2008, but the recession stalled the development, and now the developer must apply for a permit renewal.

The bi-state Potomac commission, which oversees fishing in the river, called on Maryland regulators to take a closer look this time around at the marina's potential impact on the oyster restoration effort, which did not exist six years ago.

In response, the state Department of the Environment has called on the Swan Point Development Co. to conduct a study of the proposed marina's "possible effects" on the natural oyster bar. And the state has extended its comment period on the developer's request for a permit to Thursday.

"We are reviewing it," said Thomas Blair, a state planner who's handling the permit.

Charles R. Schaller, a lawyer for Swan Point Development Co., said the developer supported the oyster restoration effort, but would have no comment on the state's request for more study until the end of the comment period.

"We're here to work with the regulatory agencies and concerned individuals and address concerns, which we originally did back in 2007," Schaller said.

He added that the developer would keep working to complete what he called an "environmentally sensitive and sustainable community," which includes two miles of "living shoreline" to minimize erosion.

In a letter to state regulators, however, Schaller called the Swan Point oyster bar "moribund" and noted that four years ago watermen reported harvesting just 11 bushels from it. Nearly a decade ago, the harvest there was 1,400 bushels, less than 1 percent of what it had been in the mid-1960s.

Gary acknowledged that the Potomac's oyster population is a shadow of what it once was. Nearly 50 years ago, the river produced a million bushels in a single season. Harvests of 100,000 bushels or more were not uncommon, but those are long in the past, too.

Like the bay's oysters, the Potomac's dwindled as a result of past over harvesting and then diseases that struck in the late 1980s. Though the diseases have abated in recent years, the river's oysters have not recovered.

Conditions in that stretch of the river can be difficult for oysters anyway, Gary said. Years can go by between successful spawns, with occasional spring floods so severe they kill many. As long as enough survived on the bottom, they only had to wait for ideal conditions to bounce back.

Gary suggested the remaining bivalves are so scattered now they can't effectively reproduce. That's why the commission wants to seed portions of the old bars with a dense batch of oysters that may stand better odds of reproducing. The rocky, shell-covered bars that once hosted oysters remain, so the commission planted oysters from Virginia on two 10-acre patches of bottom nearby over the past two years.

Officials plan to forbid any harvest on them for up to four years, then allow watermen to take legal-sized oysters with hand tongs. Those are a traditional but inefficient oystering gear that regulators figure will ensure that many will evade capture and live to grow and spawn more bivalves.

If enough oysters could be planted in the river to regain something like their former abundance, it could help clean up the river as well as benefit commercial fishermen, according to a recent study. An oyster filters up to 50 gallons of water a day as it feeds. When the bay was brimming with bivalves, scientists say, they consumed much of the nutrient pollution now responsible for algae blooms and "dead zones" on the bottom, where fish and shellfish can't get enough dissolved oxygen to breathe.

"If oysters could grow — would grow — that might help a little bit to boost the land-based [pollution-reduction] measures that are in process right now," said Suzanne Bricker, a scientist with the National Oceanic and Atmospheric Administration and the study's lead author.

The commission plans to seed the Swan Point bar with oysters next spring.