The U.S. Fish and Wildlife Service and The Nature Conservancy this week announced the completion of a dredging project that will improve fish passage on the Pawcatuck River.

The two groups removed an obstruction that was steering migratory fish away from the fish ladder at the Potter Hill Dam at the border of Westerly and Ashaway, R.I.

On Tuesday, an excavator removed an underwater berm of sand and gravel that had formed over time at the entrance to the Potter Hill fish ladder, the conservancy said in a news release. The berm was creating an eddy current below the dam that made it difficult for river herring and American shad to locate the entrance to the ladder. Adapted to swim upstream during their spring migration, fish were getting turned around in the swirling current and mistakenly swimming back downstream, the conservancy said.

The project at Potter Hill Dam is part of a larger effort to improve fish passage and reduce flood risk in the lower Pawcatuck River. In November, the conservancy and the Fish & Wildlife Service removed the White Rock Dam in Westerly, 3.3 miles below Potter Hill Dam.

The Wood-Pawcatuck Watershed Association was also a partner in the project.