Saint Vrain, South Fork - SSV - Confluence to Picnic Grounds



READ THIS FIRST: SSV was heavily impacted by the Colorado floods of 2013.  The entire riverbed was rearranged in many sections. The banks are very unstable in some sections, and rapids are expected to shift as the water levels come back up.  Scout carefully and often!  2016 update: Most people are running the section from the narrows through 1 in 5 as it's currently the cleanest and least hazard free.  The main section as it's described in the Rapids section has been largely damaged and is full of hazards and marginal lines.


SSV is one of the Front Range's classic creeking training runs.  Known for its mank and nonstop action, it brings a smile to those who love the bar room brawl feel of the run, and disdain for those who get tired of hitting rocks and taking backstrokes.  Unless the flows are unusually high, this is a good run to bring your mank boat, if you have one.  The normal afterwork run starts just downstream of a large pullout with a small restroom facility.  If flows and time allow it, putting in at the confluence of the middle and south forks offers a longer run.  The entire run is roadside and scouting is trivial.

Once you become familiar with the lines, the run is not terribly difficult, yet clean runs tend to be rare.  The continuous steep character and low volume punish upside boaters.  Holes are rarely a problem, but a few sticky ledge holes will dish out some rides and occasionally swims.  A running joke in our crew, is that on the scout, lines on SSV look terrible as you analyze every rock in your path.  Yet, somehow, the lines magically run relatively smoothly.

There is no active gauge on the South Saint Vrain, so flow must be calculated from other gauges.  The flow on this run is calculated by subtracting the NSV flow from the flow in Lyons below the confluence.  The NSV flow is calculated differently depending on whether Buttonrock Reservoir is full or not.  The primary and secondary gauges reflect the different measurements:

Primary Gauge: When Buttonrock is spilling, the NSV branch will contain the reading on the gauge above Buttonrock plus 25 cfs that Longmont pulls consistently from Longmont reservoir.  Using the gauge below Buttonrock does not account for the spill that enters back into the creek below the gauge.

Secondary Gauge: When Buttonrock is not spilling, the NSV branch will contain the reading on the gauge below Buttonrock minus 25 cfs that Longmont pulls consistently from Longmont reservoir.


A foot gauge (visual only) is located on SSV in Lyons and provides a fairly accurate measurement of the flow on this run proper.  There is a Facebook page called "South Saint Vrain SSV Gauge" where the community posts updates on the gauge level.  To reach the foot gauge from the intersection of 4th Ave and Prospect in Lyons (Prospect is the last street on the left in town as you begin to drive up the canyon), go south to the end of 4th Ave.  Walk across the bridge.  The gauge is located on the upstream side. If none of the above data is available, to estimate the flow in SSV, the upper gauges can be used, but more water will be in the actual run. 

The flow apex is around 2am and the nadir 2-3pm


Gauge links:

St Vrain at Lyons:

North St Vrain below Buttonrock:


Class V to V+
Current Flow 360.0 CFS
07-17-2024 22:43
Alternative Flow
310.0 CFS
07-17-2024 22:50
Recommended Flow Minimum: 200.0
Average: 275.0
Maximum: 400.0
Typical Season Begins: April
Ends: July
Recommended Use Kayaking: Yes
Rafting: No
Canoeing: No
Packrafting: No
Fishing: No
Length 5.0 Mile(s)
Gradient 140.0 FPM

Overhanging Rock Rapid

05-18-2013 - Fun in the mank

Photo By: Kevin Cripps

Subject: Lucas Spaulding