GOLD HILL, Ore. -- A contractor has begun removing a water-diversion dam upstream of Gold Hill on the Rogue River.

The Gold Hill Dam, also known as the Ideal Cement Diversion Dam, was built just before World War II to send water to a power house.

The National Marine Fisheries Service identified it as one of the worst threats to salmon and steelhead passage on the Rogue and told the city to remove it.

Starting Friday, the work is expected to change the river's behavior. The Rogue Valley Council of Governments urged boaters to avoid the stretch on certain days and to call staff member Craig Harper for information.