The 8.8 mile lower section is much flatter, with only Class I-II rapids, but has pleasant woods and bluffs. The lower section also includes a truly unique feature: 3.5 miles below Castleberry Bridge, much of the river's flow disappears into a quarter-mile long
abandoned mining tunnel on river left. Look for a fast-moving stream running away from the river to the left and into a big hole in the side of the mountain: eddy out at tje split to check for debris, strainers, etc. Get out of your boat and look for the proverbial light at the end of the tunnel: if it beckons, even advanced boaters will enjoy the ride. If you can't see the light from the far end when scouting, or if it is partially blocked, avoid the tunnel and stay on the main river.
There are slides in the tunnel (to correct the alignment of the crews working from each end to drill it), there's virtually no light and the noise is intimidating, so hang on, stay seated and keep your limbs in the boat for a fun ride. There's also a hole at the end of the tunnel on river right and a potentially dangerous rock shortly below the tunnel exit, also river right. Because the tunnel is extremely dark, it is important to leave enough time between boats so that anyone swimming in the tunnel can reach safety at the lower end. The tunnel is a challenge, especially at higher water levels, and first-timers should be in a group that includes someone who knows the tunnel.
According to
Roger Nott 400 cfs is OK but on the high side for the tunnel. Be alert and keep your brace handy. The rapids between Castleberry Bridge and the tunnel can be a little scrapey below 200 cfs, though the Waterfall Section immediately upstream can be run smoothly a little lower. Other than about 4 rapids, the rest of the Tunnel Section is usually fine all year round and is essentially flat water.
The usual take-out is under the Highway 136 bridge. Both banks are steep enough to be a challenge when carrying a boat and other gear, and the designated roadside parking area is 100+ yards west of the bridge. Some roadside parking is available on the east (river left) side of the bridge, the climb is easier (or, more accurately, less difficult) on river left, and a gradually climbing path leads from the downriver side of the bridge to the roadside at the southeast corner.
Directions:
To reach the access at Castleberry Bridge, take Castleberry Bridge Road west about a mile from Auraria Road (the turn is at the largely abandoned town of Auraria, 6.7 miles north of Highway 136: look for a "historical site" marker on the left or an old, brown, abandoned hotel building on right) or east about 3.1 miles from Highway 9 (the turn from Highway 9 is 5.1 miles southwest of the put-in or 2.1 miles north of Highway 136 (turn just past the tall water tank on the right)). Roadside parking is available and the access is down the path at the northwest corner of the bridge.
To reach the Highway 136 take-out, follow Highway 136 west from Highway 400 or the south end of Auraria Road or east from Highway 9. The designated parking area is roadside and west of the bridge, at the end of the long guardrail on the north shoulder of the road: parking is also available on the other three corners of the bridge. Be careful, as traffic on Highway 136 tends to move fast and lines of sight are limited.