CHINA, Maine (AP) — A species of fish has returned to a central Maine lake for the first time in generations.

Alewives, a kind of herring, reached China Lake this month, WMTW-TV reported on Wednesday. That hasn’t happened since the Revolutionary War era, the station reported.

Alewives return to Maine rivers from the ocean. However, dams have long prevented them from reaching some of their native areas, and conservation groups have spent years trying to change that.

Landis Hudson, executive director of Maine Rivers, said the group has worked to clear pathways between China Lake and the Kennebec River. That work is beginning to pay off, Hudson said.

Three dams were removed and three others had fish ladders installed to help the fish migrate.

River herring species like alewives have shown signs of growing in numbers on East Coast rivers in recent years. The fish are critically important to ecosystems because of their place in the food chain.