History & Natural History of the Middle Fork Canyon

When the miners headed into the Middle Fork American River canyon in search of gold, they came en masse. Today, over 1,500 remnants of the Gold Rush and Native American history can be found along the Middle Fork. Tunnel Chute itself is also a huge piece of gold rush history. In the late 1800’s, miners realized that gold likely settled in a slow-moving, horseshoe bend in the river. They blasted a tunnel through the mountain, diverted the river through a chute, and (eureka!), one of the biggest gold discoveries in the California foothills occurred. Many of the other relics, such as buggy wagons and powerhouses are also very captivating.

The Gold Rush

In 1848, gold was discovered on the South Fork of the American River, thus sparking one of the largest known human migrations to date. Settlers searched the banks of every creek, stream, and river in California, all in search of gold; as time went on, some of the most lucrative rivers were the Forks of the American.

By the fall of 1849, it’s estimated there were up to 10,000 men searching for gold on the Middle Fork of the American. Famous gold-yielding beaches included Maine Bar, Spanish Bar, Ford’s Bar, and Murderer’s Bar.

Early on, Hydraulic mining was often used to get at the gold in the river banks. Miners would use high-pressure hoses to divest the banks of soil and used mercury to collect the tiniest flakes of gold into one place. Hydraulic mining was banned in 1884, but the environmental effects linger today.

Over the course of the Gold Rush, California produced an estimated 750,000 pounds of gold, which would be worth $14.5 billion in 2014 dollars.

Tunnel Chute

As gold became more scarce, miners invented new ways to search the riverbanks for gold. In 1861, miners laid their eyes on a wide and slow-moving horseshoe bend in the Middle Fork of the American, believing that the gold would have settled to the streambed in this calm water. Miners tried various methods to access the streambed in the horseshoe bend, and in 1865, they began the monumental task of creating a tunnel through the granite mountainside – in fact, dynamite was only patented in 1867, meaning that much of the construction was done by hand or with inefficient (and dangerous) blasting tools.

When they finished in 1869, the dry horseshoe bend became one of the most lucrative gold sites in the history of the gold rush. As an added bonus, the famous Tunnel Chute rapid was created; this unique man-made rapid features a narrow chute and a steep drop of turbulent water which rushes through a tunnel and out the other side of the mountain. High water flows following the winter of 2016 resulted in a change to the Tunnel Chute rapid, increasing its difficulty from Class IV to Class V.


The Gold Rush of 1849 played an important role in developing the American River's rich historical identity. Auburn, Colfax and Foresthill grew to be large towns that outfitted and provided the miners with supplies. The river bars still bear the names given them by the miners. Over 6 miles long, the Grand Flume was built on the Middle Fork in the 1850's from Oregon Bar to Mammoth Bar to facilitate mining the river bed. At Horseshoe Bar a tunnel was blasted through the bedrock to divert the water from a section of river for mining. This is the site of the infamous Tunnel Chute rapid. Many of the trails in use in the canyons were miner's ditches that diverted water from streams to wash gold from the gravel at the mining camps. Much of the environmental destruction of the Gold Rush has been healed by time and now the real "gold" is in the scenic beauty, the pristine wilderness and the biodiversity found in the canyons.

Tunnel Chute

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