On a rainy October afternoon at Olson Pond, a Great Blue Heron glided gracefully over the water as a small crowd gathered for the unveiling of the Noroton Fishway Sign, which illustrates in words and pictures the story of a project to save the migratory fish that sustain local wildlife. The crowd was eager to celebrate the project, which took 10 years to complete.

“The work we did here with the Darien Land Trust, CT DEEP and our other project partners was not easy,” said Gwen Macdonald, Director of Green Projects at Connecticut Fund for the Environment/Save the Sound. “It took years of persistence and close coordination, but the end result is beautiful, functional and ecologically significant for the Noroton River and the migratory fish.”

These organizations worked together to build a fish ladder that provided passage for migrating fish along a stretch of the Noroton River that was blocked for 50 years by a culvert built under I-95, allowing river herring to return from the ocean to fresh water to reproduce.

Once abundant in the mid-Atlantic and northeastern states, river herring populations have diminished due to to water pollution and obstacles on the migration route, including dams and culverts. In the past decade, towns that have removed blockages and built fish ladders have seen their number increase. Wildlife is likely to become more abundant when river herring return, as they are important prey for herons, eagles and osprey and striped bass.

“We are very proud of the work commemorated by the sign unveiled at Olson Woods,” said Mcdonald. “We look forward to more opportunities for collaboration ahead.”

Ongoing stewardship work has already begun. Every spring, volunteers deposit a group of pregnant river herring in Olson Pond with the expectation that they will return there to spawn four to five years later. For them to survive, however, the water must stay as clean as possible. The Darien Land Trust’s next step in stewardship is to keep monitoring the environmental condition of the Noroton River and Olson Pond.

“Among other things, we want to keep the main current of the river flowing directly through the pond so that the pond doesn’t silt up,” says DLT trustee Flip Huffard. “We’re also working hard to keep the pond free of the garbage that gets flushed down the river. This spring we had a cleanup day that removed over a ton of garbage from the pond, including shopping carts, lawn chairs and many golf balls. Keeping the pond pristine is a big priority in ensuring the successful return of the river herring,”

River herring do their part as well. As filter feeders, they get their food by straining suspended matter and food particles from the water, improving its clarity and removing toxins. Given their positive impact on the environment, river herring are considered ecosystem engineers.

After a 50-year absence, a potential return of river herring back in the Noroton River is a moment worth celebrating with a commemorative sign that shares their story with neighbors and visitors to the Darien Land Trust’s Olson Woods property.