Protecting a Tidal Habitat From Pollution and Erosion

"It's a place people can find peace in an urban environment," Dierkes said. "It's going to be a 60-degree day, and the birds couldn't be happier."

When the two spied a pair of fishermen cruising the marsh in a motorized boat, Dierkes called out to them that motors were prohibited there. Dierkes's booming voice and stern warning got the fishermen to move upstream.

The Park Service prohibits organized group activities in the marsh during nesting season for the least bittern, a state-listed rare species, and the marsh wren, which is locally rare. Generally that period runs from mid-May to the end of July.

Recently, park authorities turned down a request from West Potomac High School to use the marina for crew practice and storage. A vendor has a contract with the parkway, which is part of the Park Service system, to provide wet slip rental, dry storage, ramp service, sailboat rental and the sales of soft drinks and packaged goods at the marina.

Dierkes said no new activities will be allowed until the Park Service determines the future of the marsh and the marina. A review of the marina will be done after the marsh study, which is expected to take until summer 2011. The Belle Haven study will look at the scope of commercial and visitor services at the marina.

In the meantime, the Park Service will hold frequent cleanup days. Roberson helps coordinate them.

"I just want to keep it clean," he said. "It's like you live here."

Glenda C. Booth, president of the Friends of Dyke Marsh, has been one of the biggest advocates for restoring the habitat. Nearly half of it was destroyed by commercial dredging and building debris dumped there in the 1960s.

She helped organize opposition to the marina-use request from the West Potomac High crew boosters.

"We have so little," Booth said. "We feel a responsibility to what is left."