An Earth Conservation Corps volunteer cleans debris from the Anacostia River in 2012. (Mary F. Calvert/FOR THE WASHINGTON POST)

Bob Nixon was driving over the Frederick Douglass Bridge in 1992 when he spied a curious structure under a mound of debris along the Anacostia River. “I know there’s a frickin’ building in there,” he said to himself.

Nixon cleared away some refuse, and on a pier with timber pilings sat the Old National Capitol Pumphouse. The rectangular brick building had once provided water for steam heat in the U.S. Capitol. The federal government decommissioned it in the 1950s and surplussed it to the District.

“The city didn’t even know it was there,” Nixon said, on a recent tour of the Anacostia watershed. “I thought, if we could restore the pump house, it could serve as a gateway to the river.” With support from Ethel Kennedy, he negotiated a lease with then-Mayor Marion Barry (D). The U.S. Navy, Pepco and D.C.’s water authority helped renovate the building. For 23 years, it has housed the Earth Conservation Corps, a nonprofit program for youth from the city’s poorest wards. Today, the ECC has encouraged more than 24,000 youth and adults to become environmental leaders and educators. Nationals Park is across the street.

But the future of the ECC at the pump house hangs in the balance.

Nixon is best known for co-producing the Academy Award-nominated film “Gorillas in the Mist.” A “failed biologist,” he has a conservationist’s heart. He is less known, however, for his appreciation of commercial development.

On a spring day, he drives into Maryland, to Lower Beaver Dam Creek, where ECC members and students from the Midwest are cleaning up one of the most polluted tributaries in the United States. The air smells of earth and sewage. The volunteers, who have pulled 479 pounds of garbage out of the stream, not including 10 car tires and a cement-filled tractor tire, are smeared with mud. “We do this every year,” he said. “It allows kids to get back to their roots.”

Nixon is used to giving tours to government officials and developers to enlist support for the ECC. But he has another motive for animating the cause. The District’s building boom has led Nixon and the ECC to a crossroads. The group is working with the city on a new lease because the ECC is smack in the middle of the Anacostia Waterfront Initiative, a 30-year, $10 billion economic development project. Which is what Nixon said he always envisioned: economic opportunity in the area to go along with a restored river.

He drives toward Poplar Point, a filled-in tidal marsh across the river from the pump house. The District is seeking to acquire the 110-acre site from the federal government, with plans for residences, retail and office space, entertainment and a park. He fears a land grab will diminish the site’s potential. “This is a matter of environmental justice of the highest order,” he said of the fenced-off and ecologically challenged wetlands, meadows and willow thickets. He wants to preserve the entire site for a national wildlife refuge in conjunction with the river initiative. An undeveloped 14-acre strip along the inland side of the point offers opportunities for new construction and amenities that could lure residents, businesses and tourists, Nixon argues. The ECC owns two small parcels along that stretch.

“Economic development is central to every community, and a clean environment is central to that,” he said. “This is the hill we’re gonna die on.”

Crossing over the Douglass Bridge, Nixon looks down at the pump house, as he did 23 years ago. Now it houses a raptor tracking and conservation program and a workshop for art and video production.

He relishes economic opportunities for youth engaged in the ECC or its spinoff nonprofits. “If we clean this river, we can have all this development but we haven’t solved poverty, crime or homelessness. We came to the worst river next to violent, impoverished communities, and we wanted to put these things together and see what would happen.”

Now, something big is happening. Two decades after he stumbled across a forgotten pump house covered in trash and guano and turned it into a force for conservation and social progress, Nixon may soon see his vision of conservation-minded economic development come to life.