This photo needs editing.
Difficulty IV
Length 6 Miles
Flow Range 400 - 900 CFS
Flow Rate as of: 37 minutes ago 33.3 [CFS]
Reach Info Last Updated 04/18/2015 3:21 am

River Description

Guaranteed cold and clear!  
Alto-Alto - Upper South Boulder Creek has great paddling fun from the get-go.
This classic Colorado creek run can be accessed from a variety of launch points. Put-ins range from one to four miles above Rollinsville with tricky private land river access issues and a few man-made features. The river is alpine grade steepness near the Moffat Tunnel, rolling and falling away in sections. The river then begins pooling and dropping in stage pools from mining in the Tolland Valley.

After a boater has slid under HWY 119 you will pass the Rollinsville Yacht club on river right through the thick willow then the canyon tightens.

Hit the Opener surf wave then the rapids increase and the train feels like its in the river with you if you have the luck of hitting the rapid when the train is coming.

Rapid of Note: The U.P. Cascade:
Eddy out river left to scout before the river turns back to the right and plunges down a cascade with a wall on river right and the train tracks on river left. This rapid differs tremendously between 350 and 600 CFS creating two river-wide ledges at higher flows that stomp. The static and unnatural shoreline on river left mirrors river right shoreline.

Spanky rapid is followed by a few tight turns and river splitting islands.

*Edge season fun-fact:  Long vertical icicles at head height near island splits bring on new meaning to ice cream headache.

In the exit of the canyon section a paddler will notice significant riverbed alteration as entering the private land owner whom has taken liberties with the streambed. The land owners in here (above the Icehouse property river left) have tried to create some trout habitat, apparently without consulting Gary Lacey about boulder placement.

** Unique Colorado river hazard: This is the only run in Colorado where kayakers can be run over by Semi Trucks while boating. (private land owner is trucking trailer loads of gravel out of the former Ice House property by crossing the creek daily)

Alto-Alto has a great but little canyon section, the occasional crazy naked gold miner and the front range kitty kat is home to this canyon. Beware metal sieve at railroad track crossing overhead and railroad debris and low bridge in the creekbed near takeout.

Wood frequently moves through this run, so heads up!

See Colorado Rivers and Creeks II, by Banks and Eckardt (The Bible), for info on this and most of the other cool runs of Colorado.

Lat/longitude coords are approximate, from TopoZone.

The creeks of Boulder County,
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+).

Rapid Descriptions

Put In

Class - II Mile - 0
Rapid Thumbnail Missing
The traditional put-in for Alto Alto can be done two ways a. from the pullout on Hwy 119 south of creek crossing b. by turning west onto Rollins Pass Road/East Portal Road from the town of Rollinsville and driving < 1 mile and putting in just after the road passes under the railroad.

Opener Rapids

Class - III+ Mile - 1.5
Rapid Thumbnail Missing
Just after the river leaves the tracks for the first time, you will be close against right hand wall with thickets on the left, the Opener Rapids provide the first good holes and play on the Alto Alto Run.

Lump Gulch entrance

Class - II+ Mile - 1.85
Rapid Thumbnail Missing
lump gulch enters river right as a small creek and waterfall feature just above creek level

U.P. Cascade

Class - IV Mile - 2.3
Rapid Thumbnail Missing

The creek sweeps from right to left at a rockwall, then down into this cascading rapid.

Note the railroad tracks tight against the left shoreline and a cliff wall on river right. (scout from river left at small cobblestone beach)

Island Turn

Class - IV Mile - 2.6
Rapid Thumbnail Missing
continuous whitewater follows U.P. Cascade Rapid into a ledge filled turn leading into an island that divides the current, the usual route is left around island ducking under tree branches.

Icehouse Bridge

Class - III Mile - 3.75
Rapid Thumbnail Missing
This broke-down old white bridge crosses South Boulder Creek providing access to the former icehouse property along river left. Once under the bridge, a nice play section begins and runs about a half mile.

Southern Beaver

Class - III+ Mile - 4
Rapid Thumbnail Missing
Several play holes with tall wave trains interspersed near the drainage tube coming in from South Beaver Creek.


Class - Mile - 6
Rapid Thumbnail Missing
takeout above the low-clearance railroad bridge just across from County Road 97 and the High Country Fire District Station #1


Gage Descriptions

The Colorado Division of Water Resources gauge is South Boulder Creek at Pinecliffe

Directions Description

From Boulder; drive West on HWY 119 toward Nederland, (obey the speed limits entering Nederland or pay!), go South through the traffic circle and pass by the Eldora Ski turnoff and keep climbing up and out of Ned. Enter Gilpin County and finish the climb and coast on down into Rollinsville. 

Take a right hand turn toward Moffat Tunnel/ Moffat Pass.

If you turn left toward the historic bar you will find junk food and drinks at the corner store.

(Please drive slow, there are lots of folks and dogs taking it easy in Rollyworld.)

Proceed either to the first river crossing and put-in (the standard), or.... drive the 10 miles toward Moffat Tunnel and explore some steepness and fast, clear and cold Upper South Boulder. 


Date Flow Result Factor  
2001-05-16 High Fatality One Boat Trip Read More



article main photo

Colorado Parks & Wildlife to Require Hunting or Fishing License at River Access

Kestrel Kunz

In an unexpected and strategic move by Colorado Parks and Wildlife (CPW), a Colorado hunting or fishing license will now be required to access State Wildlife Areas and CPW-leased State Trust Lands (effective July 1, 2020). Many of these affected areas have historically been used for paddling, hiking, rock climbing, mountain biking, camping, and other non-consumptive recreation uses. CPW's press release stated that "This rule is aimed at curtailing non-wildlife-related use of these properties", and while we understand the need to increase revenue to support management of these areas, we have a few concerns with this strategy. On July 1, American Whitewater, Colorado Mountain Club, and multiple other organizations submitted a joint letter to CPW Commissioners requesting that they reconsider the new Rule and find a more practicable and sustainable method for collecting fees for these areas.

article main photo

Opportunity to Participate in Upper Gunnison Watershed Management Plan (CO)

Kestrel Kunz

The Upper Gunnison Water Conservancy District in Gunnison, Colorado is coordinating a Watershed Management Planning effort "to help protect existing water uses and watershed health in the Upper Gunnison Basin in the face of pressure from increased water demands and permanent reductions in water supply." The current phase is focusing on Tomichi, Cochetopa, Cebolla, Taylor, and the Gunnison River above Blue Mesa. With local stewardship staff in Crested Butte, American Whitewater has joined the Watershed Management Planning Team to help represent recreational river users and quantify flow preferences and recreational opportunities on the Taylor and Gunnison Rivers. American Whitewater is very excited to be involved in this stakeholder driven process and we are asking paddlers to share their input on management priorities for the Upper Gunnison Basin. If you have experience paddling Cebolla, Taylor, or the Upper Gunnison Rivers, please fill out this quick survey! 

article main photo

AW releases Saint Vrain and Lefthand Creek Recreational Flow Study - CO

Nathan Fey

Longmont, Colorado - As part of a comprehensive Stream Management Plan for the St Vrain Creek Watershed, American Whitewater is collecting and compiling data on recreational uses, and identifying projects and strategies to improve stream health, recreation, and environmental conditions in the region. You can help with this extensive effort. Please participate in the Recreational Flow survey.


article main photo

Support Colorado River Access on Colorado Gives Day!

Kestrel Kunz

Colorado Gives Day is on December 4 this year and is fast approaching! Go here to schedule your online donation to support American Whitewater's Colorado River Access Program. All donations made to American Whitewater on Colorado Gives Day (December 4) will be put towards our River Access Program in Colorado. American Whitewater works to improve river access and public safety throughout the state by working with landowners and managers, paddlers, law enforcement, and lawmakers to understand Colorado's river access laws and the ongoing threats to public safety. Thank you for your support!

article main photo

Voluntary River Closure Proposed On the Slate River (CO)

Kestrel Kunz

Crested Butte CO - Alleged disruption to a Heron Rookery and concerned private landowners have led to a "Voluntary Closure" of the Slate River from the Gunsight Bridge to the Town of Crested Butte between March 15 and June 21 for the 2019 season. The Slate River between Oh Be Joyful Campground and Skyland Bridge, a 10.5 mile stretch, provides an incredibly scenic and unique flatwater paddling experience in the Gunnison Valley. The Voluntary clsoure is a product of the Slate River Floating Management Plan, created by a Working Group convened by the Town of Crested Butte and the Crested Butte Land Trust. The Working Group was created in direct response to pressure from the local community including conservationists and private landowners adjacent to the river, who are concerned that a recent increase in boating activity is disturbing a Heron Rookery that straddles the Slate River. 

article main photo

AW Comments on Colorado Nat'l Forest Wilderness Process

Kestrel Kunz

Today, September 5, marked the close of the public review process for the DRAFT Wilderness Evaluation Report. The Evaluation Phase is the second step of 4 different steps required in the assessment of lands that may be suitable for inclusion in the National Wilderness Preservation System (NWPS). American Whitewater thoroughly reviewed the DRAFT Wilderness Evaluation Report and submitted our comments to the Forest Service on September 4, 2018. Overall, we found that key paddling reaches throughout the GMUG area were greatly under-represented in the Polygon narratives and thus weren't acknowledged as contributing factors to the Polygon's respective Wilderness Ratings. We let the Forest Service know this, highlighting specific paddling reaches that should be added to each Polygon and which Polygons we believe should have a higher Wilderness Rating based on the high-quality recreation opportunities that each area has to offer. 

Please stay tuned as we continue to report on the GMUG Land Management Revision Process and in the meantime you can learn more about the GMUG here. (Photo of Josh King by Nick Spitzer)

article main photo

TAKE ACTION: Comment on the Arkansas Headwaters Recreation Area Management Plan

Kestrel Kunz

ARKANSAS RIVER, Colo. - The Arkansas Headwaters Recreation Area (AHRA) is revising their Management Plan for the first time since 2001. The new Draft Plan was made publicly available in October and the AHRA is accepting public comments through November 10, 2017 (next week!). In order to design effective and productive comments, American Whitewater has thoroughly reviewed the Draft Plan, discussed the Plan with our local Affiliate Clubs, attended AHRA Public Open Houses, and reached out to key members of the local paddling community. To make it easy for you to SUBMIT YOUR COMMENTS, American Whitewater staff have compiled our key concerns and comments for your review. 

article main photo

Colorado Honors the legacy of Matt Brown

Nathan Fey

Gunnison, Colorado - Last Wednesday, Matt Brown - longtime river guide, adventurer, and pillar of the Gunnison Valley community- passed away tragically after an accident in Moab. Matt was so much to so many.  At the request of his family and friends, contributions in Matt's memory can be made to American Whitewater’s River Access work in Colorado.  Matt was a strong ally and advisor in our work to protect the public’s rights to float and fish in the State.  We miss him immensely.

article main photo

Comments needed on Upper Colorado River Recreation Area Management Plan

Nathan Fey

Kremmling, Colorado - The Bureau of Land Management has released for public review and comment a set of preliminary alternatives for managing about 40 miles of the Upper Colorado River between Parshall and State Bridge - including Gore Canyon and Pumphouse. This is your chance to weigh in on whether there should be a day-use permit;  a camping permit with designated campsites in the popular stretch between Pumphouse and State Bridge; and expanding the developed Pumphouse Campground.

article main photo

Gore Fest 2017 is a few weeks away!

Nathan Fey

Bond, Colorado - American Whitewater is presenting Gore Canyon Festival - August 25-27th 2017Online registration is open and there are events for everyone, so sign up today! 

article main photo

A Successful River Cleanup on the St. Vrain (Lyons, CO)

Kestrel Kunz

On Sunday, nearly 50 people gathered on the banks of the St. Vrain River to pick up trash from the water and the shoreline. We started the day off with Hotbox Roasters coffee and donuts, and a few words about River Stewardship – the common cause that brought us all together. We found bedframes, rusty nails, lawn chairs, car doors, plastic water bottles, candy wrappers, fast food containers, and it doesn’t stop there. Our findings are likely a combination of leftover debris from the floods, illegal waste dumping along the river, and built up trash from years of careless passers-by. Thank you to all those that came out for the river cleanup! American Whitewater depends on our affiliate clubs, members, and dedicated volunteers in order to tackle our many River Stewardship projects.  

article main photo

Releases to Lower Dolores River certain in 2017.

Nathan Fey

Cortez, Colorado - Last week, American Whitewater met with local water managers, fisheries biologists, an other interests in Dolores River water, to start negotiating releases from McPhee Dam - like we do every spring.  This year, things are looking very good for the Dolores...

article main photo

Upper Colorado River Access funded by Land & Water Conservation Fund - CO

Nathan Fey

Dotsero, Colorado - A key river access point on the Upper Colorado river, once threatened with closure, has now been permanently protected through a partnership between BLM and Eagle County. 

article main photo

One more day to submit input on Colorado's Brown Canyon National Monument!

Kestrel Kunz

There is only one more day left to share what you value most in the Browns Canyon National Monument planning area! The Bureau of Land Management, U.S Forest Service, and Colorado Parks and Wildlife are working together to develop a Coordinated Management Plan for Browns Canyon National Monument. In order to design a plan that most benefits citizens and visitors of Colorado, the agencies designed an Online Survey and Mapping Tool to understand how the public interacts with the Browns Canyon planning area and what aspects of the area are most important to the public.


article main photo

New Report on Impact to San Miguel River From Proposed Reservoirs

Evan Stafford

Colorado - American Whitewater has released a new study on whitewater recreation in the San Miguel River Basin. The Colorado Water Conservation Board (CWCB) requested that Montrose County consult with American Whitewater on recreational needs and future impacts for the San Miguel River. Montrose County acquired conditional water rights to the San Miguel River in hopes of building multiple new reservoirs on BLM land. American Whitewater worked with Montrose County’s agents to assess the impact its conditional storage proposals would have on existing recreational opportunities. 

article main photo

Proposed Asphalt and Gravel Mine threatens the Upper Colorado River

Evan Stafford

A new proposal to allow the development of a 90- acre open pit mine in Eagle County at the gateway to the Colorado River has local river users asking questions. We encourage everyone to attend an Open House December 6 at 6 PM at the Gypsum Recreation Center, and to make your voices heard at the Town Council meeting where they will discuss the application on December 13 at 7 PM.


article main photo

Lyons Outdoor Games and Burning Can to Support AW

Nathan Fey

Lyons, Colorado - For the second year in a row, Oskar Blues Brewery is hosting the Burning Can Festival at this year Lyons Outdoor Games.  Burning Can, which takes place under the backdrop of Rocky Mountain National Park and the St. Vrain River, is a celebration of good beer, served in a can.  This year, All money raised from Lyons Outdoor Games recycled cans will be donated to American Whitewater. See you there!

article main photo

AW launches Flow Study for Yampa River

Nathan Fey

Colorado - American Whitewater is conducting a study of flow-recreation relationships for the Yampa Basin, and identifying specific metrics for use in the Watershed Flow Evaluation Tool. This study is intended to inform local, state, and federal planning efforts as to the full range and quality of recreational boating opportunities for the Wild and Scenic suitable Yampa River, as well as the Elk and White Rivers, and their tributaries. Your participation in the flow survey is requested.

article main photo

River Access Task Force Submits Recommendations to Colorado Governor

Nathan Fey

Colorado - On December 23, Governor Bill Ritter issued a report outlining a series of proposals for resolving disputes between landowners and rafters in Colorado. He also signed an executive order creating the River Access Mediation Commission to provide a way for some of the most contentious conflicts between boaters and property owners to be addressed. The Governor’s River Access Dispute Resolution Task Force was a 17-member group created in July of 2010 to help craft ways to sort out conflicts on Colorado rivers on a stretch-by-stretch basis as those disputes arise.

article main photo

Help Protect the Yampa River - Colorado

Nathan Fey

Colorado - Last month, the Bureau of Land Management (BLM) released their proposed management plan for the Little Snake Resource Area, encompassing over a million acres of soaring plateaus, wild and scenic rivers, and sweeping sagebrush basins.  Special interests are trying to overturn the Bureau of Land Management’s plans to protect portions of the Yampa River – one of the nation's last free flowing rivers.    Let BLM know that protections for these rivers are important to you!


Craig Irwin


Revision #Revision DateAuthorComment
1194027 02/16/09 Craig Irwin n/a
1196843 12/08/09 Craig Irwin
1204535 04/18/15 Craig Irwin 2015