Workers are breaching the final dams on a key section of the Klamath River, clearing the way for salmon to swim freely through a major watershed near the California-Oregon border for the first time in more than a century as the largest dam removal project in U.S. history nears completion. Crews used excavators Wednesday to breach rock dams that have been diverting water upstream of two dams that were already almost completely removed, Iron Gate and Copco No. 1. The work will allow the river to flow freely in its historic channel, giving salmon a passageway to key swaths of habitat just in time for the fall spawning season of Chinook, or king salmon.