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Everything You Ever Wanted to Know About the Bly Tunnel! (But Were Afraid to Ask) – Part One


Did you miss the other parts in our series?

Here are links so you can catch up and read them all

Part One Where we detail the physical aspects of the lake and the earliest records of exploration

Part TwoIn which we will begin to look at historic lake levels and the different natural factors which have caused Eagle Lake to rise and fall… including earthquakes!

Part ThreeIn which we retrace our steps and take a look at the various attempts to tap the lake, including 3 tunnels you never knew existed!

Part FourIn which we find out where all of this water was supposed to be going! Featuring the lush garden regions of Amedee, Standish and Litchfield.

Part FiveAbsolutely everything else you need to know about the Bly Tunnel up till now.

Everywhere we go these days people are talking about the Bly Tunnel at Eagle Lake. We all read the pertinent articles in the Lassen County Times, try and absorb facts and figures and listen to the arguments in what has become an incredibly divisive issue.

Why does this particular controversy raise the ire of so many? Just attempting to put a lot of these facts down in writing is a scary proposition given the exteme nature of the arguments. We have tried to exhaustively track down as many prima facie documents as possible, relying on the opinions or studies by experts.

Along with those opinions we hope to give you our own SusanvilleStuff primer on the colorful history, unique geology and over 150 years of political battles surrounding California’s second largest natural lake.

Before we begin I would like to point to the sources we drew on most heavily for information on the attempts to tap the lake.

First and foremost Tim Purdy’s book Eagle Lake is by far the most comprehensive study of the lake ever written. If you are passionate about Eagle Lake history you can pick up a copy of the book at Margie’s Book Nook on Main Street.

Much of the information contained within came from Dr. Robert Amesbury’s writings in his book Eagle Lake and in various essays written for the Lassen County Historical Society. Amesbury’s book, which is more anecdotal than Purdy’s, is also available at Margie’s Book Nook.

The south shore of Eagle Lake during the high water years around 1900

 Now let’s see what we can learn about Eagle Lake. The lake is 14 miles long, from 3 to 6 miles wide and, depending on the water level, there are around 100 miles of shoreline, sandy beaches, forest and semi-arid desert. It is widely known that because of the lake’s odd shape there is no place you can stand and see the entire shore. On the western side of the lake lies a lava flow almost three miles long, under which is a large body of ice. At various spots where the basaltic tubes have collapsed ‘ice caves’ have formed.

For the purposes of this essay though we will be focusing on the eastern shore of the lake, where almost all of the attempts to tap the lake have been located.There is quite a bit of unique geology at play on this shore of the lake. Studies by the USGS show more than 20 faults that converge near the Willow Creek side of the ridge, with the lake itself formed by ‘gigantic faulting.’ The fault plane extends down into the Willow Creek valley.

According to Dr. Amesbury, “Volcanic activity caused Black Mountain on the east side of the lake to increase in size, and block the outlet into Willow Creek thus forming the lake’s basin.”

Google Earth satellite photo showing the Willow Creek Valley and the lake’s former outlet ~ Click here for a larger version!

It’s easy to see in this Google Earth satellite photo how the east shore of the lake was formed. There was no Eagle Lake at the time, only a river running from the drainage down through Willow Creek. Then volcanic activity poured tons of pyroclastic material into the Willow Creek canyon, forming a huge natural dam.

Purdy says in his book that, “Eagle lake we know was formed comparatively recently, within the last one thousand years.”

The Maidu Indians have a legend about the lake which says, “Once Eagle Lake was a stream. Then it became a lake. It will become a stream again. And then it will flow away.”

Hinga Sim Mohm Dohnim, the Maidu name for the lake, means the “Forbidding Lake.”

Detail from an engraving in E.G. Beckwith’s Expedition Journal, 1854


Amesbury says, “The first record of Eagle Lake’s discovery by the white man is in the diary of J. Goldsborough Bruff who claimed to have discovered both Honey and Eagle lakes with Peter Lassen and were the first white men in that section of the country.”

Who named Eagle Lake? Although several versions of the origin have been retold over the years, the earliest reference to the name Eagle Lake comes to us from the exploration journal sent to Congress by explorer E.G. Beckwith who wrote the following in his 1854 account of the expedition; “Soon after leaving our morning camp, the road led over a high rocky butte, (which it could more easily pass around) from which we had a fine view of the lake, a few miles to the northeast. It is several miles in extent, and is set beautifully blue in the mountains which rise from 500 to 1,000 feet above it, covered with majestic pines. It has no outlet. We gave it the name of Eagle Lake. From the foot of the butte a fine spring issued, and sent out a creek towards Susan River.”

In the very next paragraph Beckwith describes what we now know was Susanville’s moment of inception!

Roop’s Fort in Susanville, ca.1872

“As we entered Honey Lake Valley, we found two brothers by the name of Roop, busily engaged in erecting a log-house and planting a small field. They had been here but a month. The lands around them at the head of the valley are very susceptible of cultivation, and are luxuriantly covered with grass and abundantly supplied with water by Susan River and other small streams.”

A report from the Army Corps of Engineers, made around 1870, is perhaps the best early description of the lake in its pristine state.

The paper says, “This [Eagle Lake] is of an entirely different character from Honey Lake, being of very clear good water and abounding with wild fowl and fish.”

“It has no apparent outlet, but about a mile from the lake to the southeast large springs exist which continually cast forth great quantities of water, and which I think must be the water of the lake which thus finds an outlet beneath the surface of the ground.”

“Without an outlet the water [in the lake] must become stagnant and bad, which it is very far from being. The springs above mentioned form the headwaters of Willow Creek, which flows in a southeasterly direction and sinks in Honey Lake.”

Interestingly the Army’s report concludes the section on Eagle Lake by mentioning that, “A scheme was talked about while I was in the country for bringing the waters of Eagle Lake to the Honey Lake Valley to irrigate the portions of the valley now reached by the existing springs.”

Click here to read Part Two of our special series 

Tomorrow, in part two of our special series, we’ll take a look at lake levels over the years, and the different factors which have caused Eagle Lake to rise and fall… plus earthquakes!

For a rather dry, but very detailed study of Eagle Lake Geology click here and download G.C. Gester’s 1962 “The Geological History of Eagle Lake.”

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