A US government watchdog recommends improved oversight of assets in the Great Lakes and St. Lawrence Seaway.

A US Government Accountability Office report looks at challenges facing the waterways, where commodities traffic has declined but boxship and passengership presence has risen.

Problems include rising pilot costs, ageing locks, inadequate infrastructure and a decline in US manufacturing.

"We reviewed modernization efforts and found that US agencies have completed almost $100 million in projects to improve locks over the past decade," the report said.