While Portlanders flock to Sauvie Island’s beaches, farm stands or pumpkin patches, one of the city’s most fascinating hikes sits quietly at the northern tip of the island, waiting to be discovered.

NEAR ST. HELENS, Ore. — It's a hot September afternoon as I set off running past farm fields into the woods on Sauvie Island, which lies at the meeting of the Columbia and Willamette rivers. It's a ...