The Winchester Dam and Fish Viewing Area is more popular than you might suspect with well over 60,000 visitors a year. It is not a well marked location, but easy to find by taking exit 129 from I-5 or going north on Stephens (Hwy 99) just into Winchester and north of Costco. (Link to map, but note it is not located on map) The facility with parking is just on the north side of the Umpqua River and on the east side of Hwy 99.
The fish you will see are steelhead, spring chinook salmon, and coho salmon. Small numbers of fall chinook salmon pass Winchester Dam but most fall chinook spawn in the South fork and mainstem Umpqua. Migratory cutthroat trout also pass Winchester Dam in small numbers. The primary non-salmonid species are largescale suckers, pacific lamprey, and northern pike minnow.