TRAVERSE CITY, Mich. (AP):  A group of U.S. senators is asking the Army Corps of Engineers to pump more money into maintaining harbors in the Great Lakes region, which has a backlog of projects.

A letter sent Friday and signed by 13 members of the Senate Great Lakes Task Force says the region should receive at least $30 million from a spending bill approved last month by Congress.

Senators Carl Levin of Michigan and Mark Kirk of Illinois are co-chairmen of the task force.

They say the Great Lakes are a vital shipping route for many raw materials, but their navigational infrastructure needs work such as dredging harbors and channels, maintaining piers and jetties and repairing lock systems.