About the Auburn-Cool Trail (ACT), with general recreation information for Auburn State Recreation Area and the American River canyons, in the foothills of the Sierra Nevada in California.

This Site Features:


A location map...

map of ACT location

Other information on the area:




Auburn-Cool Trail (ACT)

The shortest distance between the two points of Auburn and Cool follows the direct route across the 1/2 mile-long tunnel at the former Auburn Dam site. This route has been in use since the early 1970's when construction of the tunnel diverted the North Fork American River from its natural bed. It opened officially in 1996. There are three miles of 30-foot-wide paved road and two miles of gravel road built for dam construction and now seldom used. One reason for the low official use is that the gravel portions were built to low standards for temporary use, and these portions often wash out in winter. This seldom preclude its use as a trail, however. The route provides the only crossing of the river canyons above Folsom Dam besides Highway 49.

View a topographic map of the ACT and vicinity at about 1:24,000 scale. Use the Back button on your browser to return.

The Auburn end starts at Maidu Drive, just across from the buildings once used for construction offices. The road has a green gate with open field to either side and a faded sign that still says, No Public Access, as if the land were privately owned, and Construction Vehicles Only, though dam construction stopped in 1976. The way around the gate is built to the right, near the small Shirland Canal. The road goes up slightly, then downhill to intersect with the road over the abutment to the Fairgrounds area. Turn right past a fenced storage compound to go down to the river. There is a dirt road shortcut to the left just past the compound, and this is marked as the officially open route, but bikes may prefer to stay on the pavement around the curve. At the outside of the sharp bend to the left on the paved road, the trail to Oregon Bar and Rattlesnake bar comes close to the pavement but is not marked here.

The scenery from the trail is very interesting. Small waterfalls fill each gulch in spring. Remnants of stone walls, barriers to nothing, remain from the Gold Rush. Views to the south and west down the canyon show large expanses of the lower foothills with few interruptions. The falls of Knickerbocker Creek can be seen across the canyon.

Further down the trail, occasional washouts in winter may allow hikers, bikers, and horses, but not vehicles, around them. In 1986, a large segment on the Auburn side slid into the river after the 250-foot-high coffer dam just upstream broke, and the road was later rebuilt higher on the slope. In 1992, washouts required $400,000 in FEMA funding to repair.

The scene at the river bed is of a large-scale washout and dam construction, but native vegetation is gradually growing back. The river bed is a boulder garden and bikes may need to be carried a short distance until is is regraded in summer. At extreme flood flows, the river reclaims its river bed and rearranges the rocks in the channel, but soon settles back into the tunnel.

Horses on ACT at the former dam alignment

After crossing the riverbed, the trail goes up the hill to the south and below the concrete abutment of the would-have-been dam. The trail winds up and past the boat ramp site that was built 700 feet above the river bed, where Salt Creek is channeled in concrete and falls into a growing chasm of erosion. It continues up a branch of Salt Creek, crosses the Olmstead Loop Trail, and meets the paved road in the pastoral countryside of Knickerbocker Flats. Turn left on the 30-foot-wide paved road, and Cool is only 1.5 miles away. (To the right, the paved road goes to the south dam abutment, then its surface is unmaintained dirt down to the river.)

There is a route built around the gate at Cool where the ACT ends near the Northside Fire Station. This trailhead provides ample parking, water, and signboard. It is very popular for parking horse trailers. However, most visitors take the Olstead Loop and other trails from this point, not noticing the route around the locked, intimidating gate on the paved road.

The ACT is quite suitable for all trail uses. Hikers can find tennis-shoe comfort even on wet days. Horses can have wide road shoulders to themselves. On the Cool side, the paved road might just be the best roller-blading around, if anyone knew about it. Bikers can save time on the pavement and the long downhill cruises, and either walk or get a challenging workout on the climbs. Beginning bikers can go there to avoid conflicts on the narrower and more crowded trails. The trail is also the best way to simply get to the other side of the canyon, since other trails are closed to bikes and Highway 49 has increased its vehicle traffic several fold in recent years, while remaining a substandard mountain road since before the dam project started.

Light traffic on the ACT near Cool

Light Traffic on Paved Road

Click to view an Aerial Photo-Map of Auburn State Recreation Area here


1. Auburn State Recreation Area
California Department of Parks and Recreation
Box 3266
Auburn, CA 95604
Click to view a Visitor Map here

2. American River District
California Department of Parks and Recreation
7806 Folsom-Auburn Road
Folsom, CA 95630

Other useful links:

Olmstead Loop Trail about the 9-mile loop on Knickerbocker Flats near Cool, crossing the ACT

Mountain Biking in ASRA nicely unravels the busy Confluence area.

Natalie's Trails of ASRA is most complete, especially for horse riding and North Fork trails

Photos of the Trail and Canyon:

On and Near the ACT

  • Fishing Hole The tunnel outlet at about 3,000 cfs

  • White Sands Beach open but empty on the North Fork

  • Mountain Bikes Pausing at Stagecoach Trailhead

  • No This, No That Trail closures in the area

  • #