At the relicensing of a US federal dam, fishermen, boaters and environmentalists will have a chance to influence how three hydro power dams between Concord and Manchester, on the Merrimack river, are operated.

Environmentalists say they will push for dam rules that are easier on migrating fish and other wildlife that depend on the river’s natural flow.

The three dams, owned by Public Service Company of New Hampshire, are entering a five-year licensing process that will renew the utility’s licenses to run the dams for 30 years or more. The dams include Garvins Falls in Bow and Concord, one in Hooksett and the Amoskeag dam in Manchester The three dams have raised little, if any, controversy since the last licence was issued in 1980. But with the process now re-opened, environmentalists see a chance to make changes that will further encourage returning stocks of migrating fish such as Shad, River Herring and Atlantic Salmon.