Two years after the completion of a dredging project in the Upper Hudson River, a new device is helping revitalize the ecosystem in the river’s tributaries.

The “eelevator,” designed by the New York State Department of Environmental Conservation, helps young American eels access the waters above dams, which in turn feeds every level of the river’s ecosystem, said Chris Bowser, coordinator for education at the DEC Hudson River Estuary Program.

“We designed an eel ladder that could literally be lifted and raised [out of the water],” Bowser said. “We haul them up, we let them go, and then we lower the thing back down.”

These types of devices are critical because of the role eels play in the ecosystem.

“A female eel might live 20 or more years,” Bowser said. “She becomes a report card for the ecosystem that she lives in … A great ecological indicator.”

Since 2008, citizen science programs working with the DEC have caught, counted and released more than half a million juvenile eels across 14 barriers in the tributaries of the Hudson River. These “trap-and-pass” devices would hold the juvenile eels until researchers could count the fish and release them upstream.

“Imagine the Hudson River in early springtime, when the water’s just warming up,” Bowser said. “Along comes this migration of millions of Sargasso Sea-flavored snacks into the estuary at exactly the time when the river needs those nutrients the most.”

However, residents of the Village of Piermont in Rockland County wanted a lower-cost solution for a dam that was impeding eel migration in Sparkill Creek — one that could be operated by trained volunteers in the village community in addition to ecologists and researchers.

Enter the “eelevator.”

“Now that we know is functional, we’re starting to look at the next few dams upstream to see if we can retrofit those dams with these passages to allow them more access all the way up the river,” said Michelle Luebke, ecology director at the Bronx River Alliance.

Luebke manages the trap-and-pass device for eels at the dams on the Bronx River, and said passageways for eels have been established in other New York City waterways, such as the tributaries running from the East River.

Bowser added that the DEC is taking a “measured, steady approach” to expanding the eelevator program with other communities on the banks of the Hudson River and its tributaries in the future.