Boulder Creek, South
03. Gross Mountain Res to Eldorado State Park(Lower South Boulder Creek)
| Difficulty | IV(V+) |
| Length | 5.8 mi |
| Avg Gradient | 65 fpm |
| Gauge | South Boulder Creek Below Gross Reservoir |
| Flow Rate as of 1 day | 70 cfsstale data |
| Reach Info Last Updated | March 16, 2021 |
River Description
South Boulder Creek from Gross Dam to Eldorado Canyon State Park is Boulder's backyard boating flave.
Lower South Boulder Creek holds three Class V+ exceptions and is a Front Range whitewater kayaking treat with remoteness and atypical Front Range creeking challenge. Mank.
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 developed parking turnout of the turn.
Advisory: Denver Water Board property surrounds this unique putin.
Please stick to the foot trail than runs from the turnout down to the creek.
Launch from the cool mossy banks 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. As of early fall of 2020, there were at least 2 river-wide strainers which required portaging at low flows.
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 the 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 straight-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 Br
...River Features
Put-in
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
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
point of reference
this creek/draw enters river left
descending out of Walker Ranch from the North
playwave
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
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
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
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
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.
Trip Reports
Log in to add a reportin the boogie water before the forebay, dodging holes
looking down on the lead in to Martin Gulch Falls - when we cut wood, it moves ... and here it has found us again
left side very undercut
Martin Gulch Falls from the inside
pretty sweet
typical lower south boulder creek nature
Mank City, Colorado
The whole deal is a sucking undercut sieve
- wood in this drop has moved in from prior upstream cutting
this tree was rooted here, but has toppled in now and has been chainsawed at the end, beware this hidden danger when levels are >450cfs
wood here, wood there
downstream has more
its been cut, so its moving
For the full-sized version of this photo, click here.
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.
Good boat angle and on line.
Beautiful rapid - got throttled and rolled in the hole in bottom right after this shot.
350cfs range - rapid has changed since this picture was taken, rivers always changing, love it.
The old shelf boof
June 1998 flows were decent.
This upstream view shows the nature of the rapid before the rock shifted and completely changed this rapid. Hold on! This ain't over yet big daddy
Hang in there man! After the rodeo it STILL ain't over...
Watchout for the bottom hole!
This is the correct line to take. Normally this drop isn't scouted and we make the 1st timers run it blind, it's a super easy drop. But if the level is more than 250cfs going over the dam the hydraulic gets some teeth and could stop you. At higher levels there have been some awfull train wrecks with boaters stuck at the bottom and others ramming into them.
This is the first hard rapid(V-), just after the foot bridge. Mike immediately back-endered a nanosecond after this was shot. The eddy on river left is powerfull and feeds back into the hole.
We had talked to the outfitter in Boulder and I had seen it on video so no scouting just run it!The creek above was great fun!
chilly day, first time slide