Last fall, Jorge Bogantes Montero of the Anacostia Watershed Society helped to transfer tiny, hatchery-raised mussels into protective baskets in the Anacostia River. At the time, Montero said, he “didn’t have any expectations” that they would survive. But, under the careful watch of the watershed group and local school children who helped monitor their growth, nearly 92% of them did.Volunteers prepare to release hundreds of mussels that grew in baskets in the Anacostia River over the past year under a project led by the Anacostia Watershed Society. (Whitney Pipkin)

Now, the pilot project that started with 9,000 quarter-size mussels placed in a river no one was sure could sustain them has graduated to a much bigger one. In late September, the surviving mussels — some of which grew as much as 2 inches over the last year — were disseminated to several other locations in the river, from the marshes around Kingman Island to the faster-flowing waters near Yards Park.

Projects to circulate mussels through more of the Chesapeake Bay’s freshwater systems have been picking up steam as more people recognize the bivalves’ powerful water-filtering capacity.

Although most of the species used for restoration projects won’t show up on a local menu, they function like the Bay’s beloved oysters by providing food and filtration to local ecosystems.

“Mussels filter the water. They take nutrients and bacteria and sediment out,” said Jim Foster, president and CEO of the Anacostia Watershed Society. “We see this as an opportunity to help naturally clean up the river.”

Numeric labels were superglued to the shells of mussels that were spread in portions of the Anacostia River on a rainy Sept. 30 morning. The labels will help researchers identify mussels they promulgated during future surveys. (Whitney Pipkin)Researchers know of eight mussel species that are native to the Anacostia. So far, they’ve had success promulgating three of them: Alewife floaters — which grew the fastest this past year — Eastern pondmussels and Eastern lampmussels.

Montero, a natural resources specialist with the watershed society, estimates the mussels already filtered more than 32 million gallons of water in their first year and said that more reaches of the river stand to benefit from their presence.

In August, the District of Columbia’s Department of Energy & Environment gave the organization a $400,000 grant to distribute another 35,000 mussels in the river and involve 400 District students in the process. DC Water also is contributing to the project.

“Let me say that cleaning up an urban river like the Anacostia River takes a lot of hands, a lot of partnerships,”

Tommy Wells, director of DOEE, said on a boat near Kenilworth Marsh, where a few hundred mussels were released that day despite a steady rain. “You can just look out on the river today and see that this is a river worth turning back into an asset for the people who live here — and for the generations to come.”

Mussels were far from the minds of advocates determined to improve the health of the Anacostia River until

Montero started finding them in and around grass beds that his organization was helping to restore in 2015. The next year, a biologist from Maryland’s Department of Natural Resources helped them conduct a survey for mussels. They found a couple of dozen, enough to form a baseline of the river’s health and sow the seeds of a new project.

A collection at the Smithsonian Institution suggests how much of the river’s mussel population has been lost. On display are the shells of mussels that were once abundant in a stretch of the river near Benning Road around the turn of the 20th century and into the 1950s. Last year’s pilot project was a first stab at reintroducing some of those species, and it seemed to work.Jim Foster, president and CEO of the Anacostia Watershed Society, prepares to toss a pair of mussels into the Anacostia River near Kingman Marsh. (Whitney Pipkin)

“In the back of our minds, we were expecting more mortality — because it’s the Anacostia River — but that wasn’t the case,” said Montero, who reported just 8% of the mussels dying in the first year. “The food available in the water column is great, apparently. They’re not dying but growing.”

Montero has worked closely on the project with fish biologist Rachel Mair from the Harrison Lake National Fish Hatchery, located along the James River south of Richmond. The facility and others like it are spawning the next generation of mussel researchers and hundreds of thousands of mussels for rivers like the James and Anacostia.

The hatchery produces thousands of baby mussels each year and grows them until they’re more likely to survive in the wild. All three species in the Anacostia project rely on a host fish to complete their life cycle, so the propagation process is delicate.

With the DOEE funding, the watershed group plans to add two more species to the mix: the Eastern floater and Eastern elliptio. The latter seems to rely on the American eel to reproduce, and the hatchery is experimenting with in vitro fertilization techniques to promulgate it.

The Virginia hatchery grows the mussels by collecting females that already have larvae in their gills. The staff then extracts the larvae with a needle (to mimic a fish rubbing against it) or allows the mussel to release them.

Placed into tanks with their host fish, the larvae will attach to the fish before dropping off two to four weeks later to continue feeding and growing in a series of tanks.

Now that the Anacostia mussels have grown successfully in their protective baskets at eight sites along the river, the organization will test their ability to survive in wetlands and on the river bottom. Volunteers on Sept. 30 tossed hundreds of the adolescent mussels into semi-protected portions of Kenilworth Marsh, where Montero said wild mussels have been found before, “so we know it’s good habitat.”

By the end of October, Montero said, about 8,700 mussels would be spread to new locations in the river.

Sites were chosen to avoid areas where dredging might take place in the future as part of the ongoing work to remove the toxic legacy that industry left along the river bottom. The District intends to release by the end of the year a plan for initial steps to clean up contaminated sediment.

Foster said his organization is interested in the mussels’ ability to remove not only nutrient pollution but also emerging contaminants such PCBs and microplastics from the water column.

If a few thousand mussels can help clean millions of gallons of Anacostia water, he said, imagine what a few million could do.