North Fork Lewis River

This page covers the North Fork Lewis below Merwin Dam, about 16 river miles of big, cold tailwater from the dam down past Woodland to the East Fork mouth. Three dams upstream (Swift, Yale and Merwin, all PacifiCorp hydro projects) control the river, and two hatcheries sit right on it: the Merwin hatchery below the dam raises summer and winter steelhead, and the Lewis River Salmon Hatchery a couple of miles down raises Chinook and coho. The result is a river with fish in it almost every month, and a busy one, especially from boats near the hatcheries.

For a fly angler the summer steelhead are the draw. The dam releases keep the water cold through July and August, when the other lower Columbia rivers run warm and low, so the runs and tailouts below Merwin swing well for summer fish on a sink tip. Winter steelhead come in from December and peak in January and February. Spring Chinook arrive from March and peak in April and May, and fall brings fall Chinook from August, including a wild late run of bright fall Chinook, and coho into December.

Read the flows at the Ariel gauge just below Merwin Dam. Because the river is dam-fed, the flow changes in steps when PacifiCorp changes releases, not with every rain. About 1,500 to 2,500 CFS is very good for floating or fishing from the bank, under 3,000 is good, 4,500 to 6,000 is marginal, and above 6,000 there is little water left to swing a fly. The upper water above Johnson Creek has its own rules and is closed in May, and the last stretch below the dam is closed all year.