The original 1 mile trail turns to 3 miles in winter, after the road is gated.
The walk on the road is wide, and fine in boots. The trail has more snow, and microspikes come in handy. But possible to walk the entire 6 mile RT in boots, just be careful. Snow is not thick enough to use snowshoes. As it's quite wet everywhere, waterproof boots are crucial.
The waterfall is in full force, with added icicles all around. Very pretty.
For more, see http://www.wta.org/go-hiking/hikes/franklin-falls