Boulder Creek, South - 03. Gross Mountain Res to Eldorado State Park

Boulder Creek, South, Colorado, US


03. Gross Mountain Res to Eldorado State Park (Lower South Boulder Creek)

Usual Difficulty IV(V+) (for normal flows)
Length 7.2 Miles
Avg. Gradient 65 fpm
Max Gradient 175 fpm

Dam Slide

Dam Slide
Photo of Craig Irwin taken 1998

Gauge Information

Name Range Difficulty Updated Level
codwr-BOCBGRCO0 180 - 750 cfs IV(V+) 01h29m 81.4 cfs (too low)

River Description

South Boulder Creek from Gross Dam to Eldorado Canyon State Park is Boulder's backyard Colorado boating.

Lower South Boulder Creek holds three Class V+ exceptions and is a front range kayaking treat with remoteness and atypical Front Range creeking challenge. 

The Put-in for Lower SBC is 1/4 mile below Gross Dam. From the vehicle bridge that crosses the creek, park river-left, uphill in the now-developed parking turnout of the turn. Denver Water Board property surrounds this unique putin. Stick to the foot trail than runs from the turnout down to the creek.

Launch from the cool alpine mossy banks and you are right away into the cold and remote feel of South Boulder Creek, Gross Reservoir to Eldorado Canyon State Park.
Wood from recent wildfires and high water will regularly load into any drop or corner.

Ramble under a footbridge, river hooks left, eddy out left for:
* Mile 0.9, Moist Slot, Drop One, Class V, the first of the three bigger drops on this run. Eddy/scout/portage river-left. This narrow slot on river right is setup by strong cross-current seams and folding water. Enter the Slot close to right wall, paddle through the slot angled slightly left. The drop is about six feet on a sloping flake with a stopper hole to stuff you. This is a dangerous rapid. Either you feel it or shoulder your boat.

More rambling creekin' with occasional playwaves. Keep eyes peeled for mountain lions (Felis concolour) and bears as this reach holds good habitat.
Boogie-boating for about a mile until The Brain. A channelized staight-away section of the river with picnic tables on river-left indicates that you are nearing The Brain, or Hole in the Wall rapid.

* Mile 1.7 - The Brain / Hole in the Wall, Drop Two, Class V+. Eddy/scout/portage river-left. The Brain has many ledges to stuff a boater in. When run correctly, after negotiating the setup, a good landing puts you hard against the rock in the bottom. For those who portage, seal launch from large boulder just after crux ... more boogie boating for about a mile, until a flat pool is reached after the river bends left.

* Mile 3.0 Bridge Falls / Martin Gulch Falls, Drop Three, Class V+. Eddy/scout/portage river-right. Recent changes in this waterfalls geology warrant scouting. Bridge Falls is filled with wood, undercuts and fast, shallow landings followed by a stomper hole. After Bridge Falls pass under a footbridge and enter a beautiful Class IV cascade into more canyon that emerges into a forebay.

*Mile 4.2, Forebay and the Dam Drop - Eddy/scout/portage river left.
The route over the Dam is right. Be four to five feet away from the righthand wall in the righthand chute. Dam Drop is about 30 feet high and on a slight angle just off vertical. After the dam drop, over half the water in the river is stolen away to the thirsty pipes of Lakewood and Denver. Prepare for about 1.3 miles of boneyard shallows (90 to 120cfs).
Attempting the de-watered section with less than a 125cfs on the lower gauge (Eldorado Canyon, 1*7*) is not recommended. Rental boats preferred.

*Mile 6.5, Take-out river-left in picnic grounds, free food for kayakers!
or *Mile 6.7, Take-out river-right upstream of the green vehicle bridge Below this bridge leads into Class V+ Eldorado Canyon and Harmon Falls.

Shuttle is about 50 minutes one way. Bumpy Boulder County backroads and dusty washboard gravel roads around Denver Water Board property.

For descriptions of Colorado runs, see Whitewater of the Southern Rockies by Stafford and McCutchen, or Colorado Rivers and Creeks by Banks and Eckert.

Lat/longitude coords are approximate, from TopoZone.

The various reaches of Boulder Creek,
Jasper Creek (Class V+/VI),
The Source (Class V),
Upper Boulder Canyon (Class V/V+),
Lower Boulder Canyon (Class IV),
Boulder Town Run (Class II/III),
North Fork Boulder (Class V+/VI),
Alto-Alto (Class IV),
Upper South Boulder (Class V+/VI),
Lower South Boulder (Class IV/V+/VI),
Eldorado Canyon (Class V+).

Spiders abound

StreamTeam Status: Not Verified
Last Updated: 2018-11-07 08:15:15


Stream team editor

Rapid Summary

Mile Rapid Name Class Features (Legend)
0.9Moist Slot-Drop One5.0Portage Waterfall
1.0Davis Gulch enters river leftII
1.7The Brain -Hole in the Wall -Drop Two5.1Portage Hazard Waterfall
3.0Bridge Falls -Martin Gulch Falls -Drop ThreeIVAccess Portage Hazard Waterfall
4.2The Dam DropIIIAccess Hazard
6.0take outII+Takeout Access

Rapid Descriptions

Put-in (Class II)
West from Boulder on Baseline Road climb over Mt. Flagstaff to Gross Reservoir. Take left on a dirt road to below the dam. Denver Water Board does not allow boaters to put in at the bridge. Park up the hill downstream from the bridge in an obvious pull-out and hike down to the river.

Moist Slot-Drop One (Class 5.0, Mile 0.9)
The Moist Slot is the first of three Class V (V+) drops on this run. Pass under a foot bridge, river hooks left, eddy out river left, then you are headed into the slot on river right. The Moist Slot drop is about 6 feet and the hole does drive you toward the right wall. Some call this rapid Hole in the Wall. Hit this hole with determination, or it will hit you, for a while. - portage river left-

Davis Gulch enters river left (Class II, Mile 1.0)
point of reference this creek/draw enters river left descending out of Walker Ranch from the North

playwave (Class III, Mile 1.3)
just after you seen Davis Gulch enter river left, watch for eddies and find the play wave (typically found at 350 ~ 450 cfs)

The Brain -Hole in the Wall -Drop Two (Class 5.1, Mile 1.7)
The second Class V (V+) rapid of this run, the Brain just looks dumb, all water goes into an undercut rock in middle of river in the middle of the drop. After a few fun rapids upstream, the channelized lead in is straight into a pile of rocks. This rapid has a 24" slot to negotiate and this rapid could stuff you under a few rocks. A good run will put you against the wall at the bottom, or so says Eric Bader. Alternate idea: portage river left, seal-launch from rock in rapid after the junk. This rapid is ugly. The portage is easy, its your call.

Bridge Falls -Martin Gulch Falls -Drop Three (Class IV, Mile 3.0)
The third Class V or V+ rapid on this section of USB, Bridge Falls or Martin Gulch Falls. This drop used to be boofed river right, tight up against the wall, landing in a poool, then rambled down a fast shallow channel river right into the bottom hole. Wood is always a hazard here. The run is now up to you; left or right. The right side is less of a boof and more of a hazard with rocks in the landing now. The left side can be undercut and tricky, but is manageable. Very junky. Note: this rapid changed significantly in 2001: The pool has reduced in size and the entrance boulders have all moved. Take a look at this one. The hole at the bottom of this rapid will work you like a ragdoll in a planer, so for God's sake, boof with intention. Portage is river right from beach head, with a nice stone foot trail for 80 yards, then put-in above bridge and prepare for fun class IV cascade.

The Dam Drop (Class III, Mile 4.2)
a brainless big drop over a 25'~ 30' dam run 5' from the right hand wall point straight and lean back eddy river right Do not let anyone run center or left at low or high water, rock garden at low water and terminal recirculation at high water. Denver Water Board has a road accessing the Gauging Station and dam here. dam elevation is 6,200'

take out (Class II+, Mile 6.0)
After running the dam, the water is stolen out of the creek and piped to the eversprawling Denver suburbia. You will pass through a patchwork of state park and homesteads along the creek in combination with splitting channels and low bridges. Take out after picnic grounds on river left in a river-right parking lot just above the green bridge that crosses the river. You are in Eldorado Canyon State Park. Harmon Falls is downstream.

User Comments

Users can submit comments.
June 5 2005 (4936 days ago)
Fremont ShieldsDetails
Moist Slot rapid has a hidden (at >250 cfs) sieve on river right about 15 feet after the initial
slot drop. The right side of the the entire drop and the ensuing hole are undercut, too. Be aware
that accidents have occurred here when considering this drop.

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Associated Projects

  • Gross Reservoir (CO)
    The City and County of Denver is looking to increase it's water supply, and has applied to both the US Army Corps of Engineers for a permit to enlarge Gross Reservoir, and FERC for a hydropower licens