The Tunnel

and River Restoration

A river runs through it...
The 30-foot wide tunnel: a river runs through it

The half-mile tunnel in the bedrock at the former Auburn Dam site provides a bridge across the North Fork American River for the Auburn-Cool Trail. This is the only river crossing above Folsom Dam besides Highway 49.  Thus, the tunnel allows trail access across the canyons as well as river boating access down the river to Folsom Lake.

The Placer County Water Agency and U.S. Bureau of Reclamation are planning to close the tunnel to install a permanent water diversion facility. The plans call for restoring the river bed after closure of the tunnel. The work would begin in mid-2002. The Environmental Impact Statement/Report is available from SWRI ( in Sacramento but comments closed December 13, 2001.  Additional comments on the proposed project may be made to the California Regional Water Resources Control Board, Regional Water Quality Control Board, California Department of Fish and Game, and U.S. Army Corps of Engineers.  The State Lands Commission claims ownership of the bed of the North Fork American River.

Location Map

map of tunnel location

One justification given for the closure is that the tunnel is unsafe for boating. But there has never been an accident or injury there, and it remains safe during the normal summer boating season. And only above about 2,500 cubic feet per second of flow volume in the North Fork (such as during floods or heavy spring runoff) would the tunnel be filled with water at the outlet. For its 20 year history, the tunnel has been safe, and should not be used to justify engineering. The closure is for water diversion rather than for safety or restoration.

The once and future river bed...

Yet, the former dam site could definitely use some restoration. The $327 million concrete abutments stand in stark contrast to the rest of the oak-filled canyon. The washout of the 250-foot coffer dam in 1986 left huge scars that continue to erode, with large broken pipes sticking out in a precarious manner. Hasty roadbuilding for the project has contributed to landslides that have caused sedimentation and increased turbidity in the river downstream and in Folsom Lake. The cost of seasonal repairs on the service roads alone has run into the millions of dollars, and many roads remain cracked and unsafe. The tunnel is the last reasonable place to seek improvements in safety at the former Auburn Dam project.

View of the former damsite

Restoration of the river should begin with the large-scale disturbances created on the hillsides as part of the Auburn Dam project.

The plans for the diversion and permanent pumping station are well underway. The planning process has been limited to local publicity. Curiously, local environmental groups went along with the diversion of the river so the channel could be 'restored' to the river. Thus, the good news is the river will go into its old channel. The bad new is that it will then be diverted to another drainage. Diversions are expected to increase gradually to a high level of 200 cubic feet per second (cfs) once the permanent, expanded facilities are in place. Previously, the temporary facilities only diverted up to 50 cfs during summer for small-scale irrigation. The additional water will now contribute to other developments in the region. The tunnel closure, without the addition of a new bridge at the site, will severely impact recreation access in the area.

View the Tunnel project site and current status.

View the water diversion scheme proposed for expansion.

View the 'preferred alternative' to get more water from the river.

What this means...

Less water in the river and loss of access across and along the river canyon.

See also:

Top Ten Trails of Auburn State Recreation Area

Boating the Forks of the American River

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