Written by John Kosakowsky
John Kosakowsky is the President of River Runners. He is an avid boater and educator of new boaters and commercial river guides.
From the parking lot 400 vertical feet above the put-in, it’s easy to feel intimidated. At first sight the river falls over a ledge, crashes into a rock, and spits a rooster tail wave into the air. The setting is stunning. A quarter mile downstream from put-in a magnificent waterfall cascades into the river in a narrow granite gorge fecund with oaks, mosses, and ferns. All this beauty and madness inspires the strenuous act of carrying the rafts and river gear down a steep hill to meet it. Welcome to adventure. Welcome to aqua incognita. Located just upstream of the popular Chili Bar run on the South Fork of the American River is this hidden gem we locals call Slab Creek. The run offers 8 miles of awesome class IV+/V seldom experienced due to the inconsistency of flows. Nevertheless, Slab Creek has a big reputation because of the quality of its consistent whitewater.
Slab Creek Dam is a 250’ arched wall of concrete and rebar built in 1967. It diverts up to 3800 cubic feet per second (cfs) into a tunnel snaking eight miles west toward the White Rock Powerhouse where it rejoins the riverbed just below Chili Bar reservoir. This effectively dewaters the canyon, since the water is so well-managed it rarely escapes back into its native environment. In the 1960s, the riparian zone was sold down the river to protect and electrify the Sacramento Valley. When the operating agency SMUD negotiated the water rights with the federal government, the river was left with a minimal flow. It averaged 150 cfs for 50 years--just enough to support life, kind of--but not enough to support recreational boating. In fact, the valve at the dam’s base could only release a trickle of water. The great waters of the South Fork of the American were gelded by engineering. Until recently…
Slab Creek Dam is a 250’ arched wall of concrete and rebar built in 1967. It diverts up to 3800 cubic feet per second (cfs) into a tunnel snaking eight miles west toward the White Rock Powerhouse where it rejoins the riverbed just below Chili Bar reservoir. This effectively de-waters the canyon, since the water is so well-managed it rarely escapes back into its native environment. In the 1960s, the riparian zone was sold down the river to protect and electrify the Sacramento Valley. When the operating agency Sacramento Municipal Utility District (SMUD) originally received their hydropower license from the federal government, the river was left with a minimal flow. It averaged 150 cfs for 50 years--just enough to support life, kind of--but not enough to support recreational boating. In fact, the valve at the dam’s base could only release a trickle of water. The great waters of the South Fork of the American were gelded by engineering in what is known as the Upper American River Project. Until recently…
Every 50 years, dam operators like SMUD are required to re-license their hydropower project. This process is governed by the Federal Energy Regulatory Commission (FERC). At this time all parties interested in using the water come to the table to lobby for access and flow. The new license was issued in 2014 and Slab Creek dam is currently in the implementation stage of this 50 year license. Thanks to the policy changing efforts of many environmentalists, advocates, and concerned citizens, SMUD has had to redesign their dam to include a valve capable of releasing a “boatable” flow*. Up until now, boaters had to hope for a storm big enough for the dam to spill over. Now a complicated agreement guarantees very minimal recreational releases depending on snow pack levels and/or use.
On September 6th, 2017 SMUD stopped diverting the river through the tunnel so they could install the new valve that will release the increased flows. The dam became a 250’ waterfall, and all of the river water began flowing in its natural course again. This initiated the first consistent recreational season in this canyon since whitewater boating became a pastime…and a new chapter in my intimate relationship with this river.
I have a deep personal relationship with the American Rivers. I swam here before I can remember. I grew up very near Slab Creek Dam on the South Fork of the American River. My siblings and I loved to hike down to the riverbed below the dam to explore. We sauntered around, finding out that ladybugs bite and newts live in condominiums of moss and stone on wet hillsides. I took the dam for granted, and in a way, I thought of it as a playground. In 1997 when I was 20 years old, I paid for my first commercial river trip on the Chili Bar section and in 2000 I became a commercial river guide on the South Fork. I now co-own a rafting outfitter specializing in American River trips.
After guiding commercially for a few years, by 2005 my thirst for river exploration was unquenchable. I bought a shredder, a raft, and a kayak, and started an investigation of California’s whitewater wonderland. It was spring and a great water year, so I enlisted my siblings and friends and we went out to explore. We didn’t have much skill back then, and relied on our youth, inspiration and serendipity. We referenced Dreamflows for data and write-ups and had long days full of scouting and unintentional swims on sections like Golden Gate, Potwisha, Devil’s Nose, Middle Fork of the Cosumnes and 49 to Bridgeport among others.
It was during this period that we first ran Slab Creek. We had absolutely no beta on the run. It was a harrowing affair. The flow was a healthy 1200 cfs. We started in the morning and ended at dusk. We were outgunned. We parked the raft at most horizon lines and stared down at the complicated lines. Though hesitant at times, we pushed ahead through many near mishaps. We fell out at the top of Mosquito Bridge rapid and swam all the way to the bottom. We recovered most of our paddles thanks to my brother Daniel’s prodigious skills. We met Mother Lode Falls, a big class V series of drops and holes. At that point, I think everyone was beat down enough to just pull the boat through the slick boulders instead of hazarding the challenging line. The rapids calmed down after that, and we found ourselves paddling across Chili Bar reservoir in the deep reverie that near-death adventures bring. Little did I know the Slab Creek run was about to dry up, again.
After that first run, Slab Creek mostly eluded us. We often stared at Dreamflows willing the river to rise. It rarely did. One morning at 7 am, my brother ran by my tent yelling, “Slab Creek Dam is spilling.” We were on the river by 9 am, slaloming through rockpiles on 600 cfs. It was a lot less intimidating at this flow. Another time, we put on in the early afternoon, and the water dropped to less than 400 cfs. We didn’t get out of the canyon until 10 pm. After these experiences, I decided that it was too unreliable to be fun, and not worth planning for. The river came up in 2011 thanks to a wet winter, but it stayed too high for comfort, then the drought began, and we didn’t even bother looking to see if Slab Creek was an option.
In the Fall of 2017 word spread that Slab Creek was open, but because of our prior experiences I wasn’t that interested at first. My brother Daniel went out there a few times and came back with stories of good times. In December, I finally decided to give it another chance. From the put-in to Mosquito Bridge the river drops 400 feet in four miles. Every rapid has class IV features, and some feel even harder. It is classic pool-drop, but there isn’t much flat space between each of the drops. The first two rapids are really testy. They are aptly named Casting Call, and Prologue. It gets a tad easier as the lines open up a bit more, but that’s not to say it’s easy.
There isn’t much small sediment in the riverbed, and the whole course is a series of serpentine currents crashing into large boulders. It’s a wide gorge with the water crashing against solid walls and building big ledge drops and wicked cross-currents in narrow places. About a mile above the Mosquito Bridge, the gradient increases and the rapids get longer and burlier. This means longer scouts if you don’t know the way. The bridge rapid is tricky, and it’s more common than not to see swimmers struggling to get themselves to shore before the sheer walls make the bridge inaccessible. Below the bridge, if you choose to go the full 7 miles down to the Rock Creek take-out, the gradient picks up and the sieves grow more dangerous. And then there is Mother Lode Fall: at low flows (500cfs) we were R1ing the boats down or portaging on the left, at higher flows we ran a sneak line on the left. It’s a lot to deal with. At least things get easier after the falls. There’s still couple of class IV rapids including one called Pamplona since a swim here would feel like running with the bulls.
Slab Creek is not introductory class IV. I have read it described as “a notch above Chamberlain's and a notch below 49 to Bridgeport.” That is especially true above 1000 cfs. One day we arrived at put-in to find two lonely rafters in a 10’ Hyside raft. Since we were having a dry December, they had decided to give Slab Creek a try. I was very concerned about them and suggested they run with us. The river rose to 1500 cfs, and that made for some pretty serious consequences. One of the guys fell out in the second rapid, Prologue. Just a mile downstream, they were terminally surfed in a ledge, and we had to hike back upstream and rope them out of a rapid we now affectionately call Kelby’s Hole. A little while later, they flipped in a giant feature called Head for the Bushes, then in the next rapid Santa’s Surf. And finally, they both swam in the Mosquito Bridge rapid. Their boat washed 500’ downstream of the bridge where they were taking out that day. I was glad we were there to support them, especially since I myself had been humbled there. The river has a way of rounding the corners off a boater’s personality.
I logged 8 trips on Slab Creek in December and January (some friends of mine rafted it 20 times!). The flows varied between 550 and 1600 cfs. At the low end, we R2ed 10 and 12 foot rafts. You can run all of the holes at low flows and are more worried about big rocks in the way than anything else. It’s a beautiful slalom course and it isn’t very pushy which is nice. At flows around 1000 cfs, a 13’ raft is ideal as there are really powerful drops and holes that want to surf your craft. At 1600 cfs it’s fast and powerful. There are at least 3 river wide ledges that have only one weakness to drive through. The lines are blind at times with the waves crashing high into the air. It starts to feel closer to Class V, and I’m sure the swims would feel at least that serious.
Since my first run out there in 2005, I have gained a lot of river experience: it’s come in the form of thousands of miles logged, and some life-changing swims. After years of disinterest, I find a great source of inspiration right here a few miles from where I live. It’s been nice to reacquaint myself with Slab Creek, and I now consider it a quality run with so much to offer for both the experienced boater and the ambitious newbie. I have fallen in love with a new river canyon. Heraclitus said, “No man ever steps in the same river twice, for it’s not the same river and he’s not the same man,” and yet again I find that to be true.
On January 16th, 2018, the diversion tunnel came back online. The window of opportunity to test those waters has closed as a mere 100 cfs now courses through the canyon. At this point, unless a rogue storm pushes the reservoir to overflowing, the Slab Creek run will only be available for recreational boating a few days a year, on prescribed weekends in the spring. The really cool thing is we recreational boaters have a say in how accessible it is. If enough people attend the releases, there will be more. We will get them even in dry years, and in the fall too! I see a new whitewater festival in the works, a compliment to Feather Fest and Gauley Fest. If we can get enough participation in the forthcoming releases, it will happen. And maybe, 50 years from now, when the FERC license comes up for review, we can find a way to return even more water to this beautiful riverbed.
Long live Slab Creek!
* The advocates for recreational releases were; American River Recreation Association, American Whitewater, California Outdoors, California Sportfishing Protection Alliance, Foothill Conservancy, Friends of the River, Hilde Schweitzer (private boater) and Theresa Simsiman (private boater)