On a sunny day in late April, the Duckabush River glistened as it neared the end of its journey from its Olympic Mountain headwaters to the breezy tide flats on the edge of Hood Canal.

Flowing clear over cobbly stones in the shallows, steel blue in deeper parts, the current moved swiftly, fed by warm-weather snow melt on peaks up the river valley, some of which could be glimpsed on the horizon. Between 50 and 100 feet wide in places, the river was not roaring but was moving fast enough to maybe give you pause before wading in.

The Duckabush is not dammed and is otherwise relatively undevelo...