The Alsea Falls Recreation Site is open May 1 through September. I'm not sure if the day use is accessible either this time of year which is where the falls are. Check this link: https://www.recreation.gov/camping/campgrounds/255205
Day use area is accessible year round. I have been there in every season and the trails and falls are accessible, as is the main bathroom at the day use area. The campground area 8s summer only
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