Answers, I hope. (the link search on this thing really chews puppy butt)
The online gage for Northgate is: <http://waterdata.usgs.gov/co/nwis/uv?format=gif&period=15&site_no=06620000>
1000 cfs+ is fun for all. 900 means big boats will hit a few rocks and small ones need maneuvering. Below that, it's a workout.
We ran Saturday, at 900 cfs, on the tail of a rainstorm peak, in brilliant sun. The snowpack's low, so there might not be a real high-water blowout this year.
Put in: Routt access, a short right off CO 125, just S of Wyoming border (river in sight). Ramp is a flight of cement steps with rails to slide boats down to river.
Take-out: Six Mile Gap: (CO 125 changes to WY 230) R off hwy about 2 mile, through campground to river parking. River access is a 1/4 mile of steep (but maintained) trail— all gear must be carried up to the parking lot (i.e. light is right).
Shuttle (easy) takes about 40 min. R/T, mostly on pavement. Hitching (or paying one of the outfitters to take you) is a fair bet on weekends Sketchy on weekdays. (Not a bad bike ride.)
The float is about 5 hrs, most of it flat or gentle water. The more difficult rapids are concentrated towards the end. At 1000-1500 cfs (now), I'd rate it 3+, adding a bit as the flow increases. Above 3000 cfs, Narrow Falls flips quite a few rafts: call it a 4+ or a 5. At 5200 cfs (10 yr. flood, in 2005) most boats flipped and some people took long swims.
Main rapids from the Northgate ramp to Six Mile Gap (with notes) are:
-Windy Hole: around first left bend, left run, nice bounce. (then, lots of flat water with small rock gardens)
-Cowpie: a couple hours down. Rocks get tighter over a quarter-mile, with the crux a right run around the cowpie (big mushroom-shaped boulder) then a hard left pull, followed by tail waves that break at higher flows, and rock gardens.
-Narrow Falls: cliffs pull in, ledges and large boulders funnel the flow to a center slot, with a steep drop (I usually go in just right of center) and an immediate pull right, for the big eddy. Left is an undercut cliff face that flips boats, and a rock fence that stops rafts. Kayakers can scout left. Rafts sometimes have trouble ferrying from there back to the best line. At lower water (1000-) rafts can stop just above the falls and scout right. (Line the boat upstream and then pull like a dog to get back in the current.)
At higher flows, boat-scout and give it a go.
-Tootsie Roll: longer & continuous. Large boulders and ledges overlap and step down, with pourovers and several sneaky holes (hard to see from the top). I stay loose, and run mostly to the left.
-Stovepipe: rock garden that forms holes at high flow. Zoom right, avoiding the cliff. Then move left. At the tail, pull far left at the rock tower to make the landing at Six Mile Gap (the channel splits).
(There's a board at the Northgate put-in with a rough map- good for relative distances.)