The Narrows of the Cache La Poudre can be broken down into three sections with different characteristics.
_Upper Narrows_
The "Upper" section consists of three drops: Super Collider (V), Cabbage Shredder (IV), and Whiteline (V). These drops are back-to-back and easily scouted from the road; be careful because there really isn't much of a shoulder and lots of traffic travels along this road. Only a few years ago the Upper Narrows, particularly Whiteline Rapid, were considered deadly class VI rapids.
_Middle Narrows_
The "Middle" section is good all-around class IV section of whitewater, and is great for those who want to add a little more class IV mileage to the Upper Mishawaka run; if this is your intention, don't forget to portage Lower Narrows! And watch out for Sports Car Corner, the first significant drop in the Middle Narrows. This is a manky drop with consequences for the upside-down boater.
_Lower Narrows_
Just below the Highway 14 bridge is the Lower Narrows, which consists of one big burly "classic" class V. This is a fantastic rapid with a bunch of neat moves, and eddies that all you to catch your breath at most levels, and a very aesthetic position alongside the road. A messy rock jumble at the bottom of this rapid gives you incentive to stay on line! For those who are running the Middle Narrows for the class IV experience, you can easily take-out on river left above the bridge and portage to the put-in of your liking on river right at the bottom of the Lower Narrows and continue on down to Steven's Gulch Access.
Appropriate levels for these sections vary tremendously. The entire section is commonly run at less than 1' on the Pineview gauge up to about 2'. Above 2' or 2.5', the Upper and Lower start getting burly, but the middle is excellent. Above about 3.5', the Upper and Lower are much less frequently run (they're moving into the V+ range at those levels), while the middle is pushy and burly IV+ or "easy V" and a whole lot of fun. This short run holds a lot of great whitewater.
Locals have been know to run this down to about 50 cfs when they are desperate for a whitewater fix. It's possible to get down, but very bony at less than 150 cfs.
Logistics:
To get there: The put-in for the Upper Narrows is at the Narrows Campground or the large pull-off just above Super Collider. For the Middle Narrows, put-in at the base of Whiteline--the really steep constricted rapid--or just down stream at the sharp corner. Parking is very limited with small pull-outs on blind corners. The take-out is at Steven's Gulch Access, a very nice improved picnic area and launch site with changing rooms.
For descriptions of Colorado runs, see:
Whitewater of the Southern Rockies by Stafford and McCutchen or Colorado Rivers and Creeks by Banks and Eckert.
The most reliable flow information, and a calculator for converting cfs to/from the Pineview gauge, is available from the Poudre Rock Report at
http://www.poudrerockreport.com
More runs in the area:
Big South (Class V/VI),
Joe Wright Creek (Class V),
Spencer Heights (Class V/VI),
South Fork (Class IV/V),
White Mile Run/Upper Rustic (Class III),
Grandpa's Gorge/Lower Rustic (Class III/IV),
The Narrows (Class IV/V/V+),
Upper Mishawaka (Class III/IV),
Lower Mishiwaka (Class III),
Poudre Park (Class IV),
Bridges (Class III/IV),
Upper North Fork (Class IV/V),
Lower North Fork (Class II/III), and
Filter Plant (Class III)