Assuming you are referring to the Lewis R. hatchery at Cedar Cr. on the North Fork of the Lewis:
Take I-5 south to Woodland.
Take the left going under the freeway.
Heading east take the first right which goes over the N. F. Lewis R.
Over bridge stay left going east on Co Rd 16, follow it maybe 8 mi. to Co Rd 20 take a left and follow signs. A little over a mile you'll come to boat ramp facility on the south side of river.

To get to north side of river:
Simply stay on Hwy 503 after going under the freeway.
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Matt. 8:27   The men were amazed and asked, “What kind of man is this? Even the winds and the waves obey him!”