How can I find out when Chinook salmon start arriving in Idaho?

Avid anglers will follow salmon returns by checking the dam counts at Bonneville Dam (first Dam on the Columbia River). A general rule of thumb is it takes about 14 to 17 days for salmon to travel up the Columbia River to Lower Granite Dam, the last of the eight dams they must pass over to reach Idaho.  The travel time can vary based on run of Chinook salmon you are following and what flows are like.  For the most part, those fish migrating in higher flows will take longer than fish traveling in lower flows.