The Mystery of Lost Lake of the Cajon Pass

It is not known to many people, but it is still possible to use the old highway up through a portion of the Cajon Pass. Present day highway 15 runs well above old 395 and Historic Route Highway 66. Such rustic areas as Blue Cut and Halls Ranch (Yes my Family again), and Sullivan's Curve still exist.

As you drive up the badly surfaced road from Devore (Use the Kenwood Exit from the Northbound 15 and make a left, pass under the 15 and then make a right on Cajon Blvd [old 395 & route 66]) you notice that for the most part you are driving on what would be the southbound lanes of the old 4 lane highway. As you come around the curve at Blue Cut you notice that there is now a mountain sitting over the right-hand lanes into the center divider. You might think that this is ample proof that the San Andreas Fault zone is alive and moving. But you would be wrong. It is actually the San Jacinto Fault Zone that straddles the highway. The San Andreas is still one mile ahead.
Two Faults zones so close together and visible? As you proceed north you notice that the entire area between the faults is moving to the north and at different speeds. Only 2 or 3 inches a year, but they are moving. So much so, that railroad crews from both the Union Pacific and Burlington Northern Santa Fe, have to go out twice a year and reset the tracks. Otherwise, the train tracks would bend out of shape, just like old 395 has.

As you proceed, you will see a sign that says 'Lost Lake'. It also says private road so most people ignore it and just keep heading up towards Sullivan's Curve. Sullivan's Curve by the way, is a favorite Train Watcher area and has also been the scene of several major train accidents over the years. The best way to get into this area is to exit highway 15 at Cleghorn Pass Road, make a left under the freeway if you are going north bound that is and then make a right on the first roadway you see. This will take you back to a triple track bypass area, a small yard, and the beginning of the lower end of Sullivan's Curve.

But if you take the time to make the left turn onto the dirt road and cross the triple set of tracks that tend to hide it's route, you eventually find a quiet little area that should not exist. For there are no streams, creeks or rivers that feed into Lost Lake. The water seeps up from beneath the ground. A direct result of two major earthquake faults zones passing within a half mile of each other.

Some say that Lost Lake has no bottom, that it feeds directly from the center of the earth. The water is also very cold, below freezing even in summer time. Fire crews have used its water supply to help fight fires, and they have never noticed a drop in water levels. It always stays the same, even in heavy rain seasons. And snow fall has no effect on it. But it has never frozen either.

Lost Lake is surrounded by lush grassy vegetation, some what like what you might see back in Kentucky or Tennessee. In fact Kentucky Blue Grass grows all around the lake.

As you drive further into the narrow valley you realize that both fault zones are coming together. All of a sudden you run into a wall of a mountain that blocks your way. You can climb up this 500 foot high rock fall and look out over the valley you have just passed through. To the northwest are the 10,000 peaks of Mt Baldy, Cracka Ridge and the Mountain High Ski area. As you hike through the area you become aware of how insignificant you are amongst the grander of the Fault Zones, the Mountains and the trees.


I am her sister inlaw it did happen and was so tragic for all of us. Thanks for a friend and helping her with this. God bless you and of course her.

I have. My two sisters. They were, I believe, 1 and 2 (I was about 10 years old). I know your post was several years ago, but I hope you still check it.

The Lost Lake was beautiful! Almost impossible to find.

My very good friend took me there. He told me about how when he was younger he used to go four-wheeling at Lost Lake, and dive into the lake and go swimming. Two people told me that there was 2 or more "lost lakes". All I know is that when my friend took me to the lake, I had to look almost completely straight down. And I took pictures. It's beautiful.

I'm from Florida, and we have no mountains nor hills. So to see something like that was breath taking. We went close to the water. I would say that we climbed down but it was more like sliding down. I tried to climb back to the top by the golf course, but I kept sliding back down.

I thought that was a really nice surprise. Like a late birthday gift, or birthday surprise. :D

How do i get to the Lost Lake, and is there a fee?

The Lat./Long. coordinates of Lost Lake are:
34.273, -117.4655
You can enter those coordinates at most map websites in their search box.

215north get off kenwood.make a left.go up cajon pass until you get to your first left turn, continue going straight passing two train tracks, you will eventually see an opening in the road allowing you to turn right you will see a restroom and something that looks like its blocking you from entering but don't mind that just park walk up the little hill then there you are. Yes you need a mountain pass to park up there that u can buy at a gas station up there

Urban legend. It is not bottomless. Lost Lake water supply is not visible above ground so people imagined it bottomless.

The entire valley was a lake in prehistoric times and underground streams and springs still exist. Ever see steam coming out of storm drains on E Street? That is from hot springs below the city. There are also tunnels once used by Chinese immigrants. Dad visited them often as a child.

Lost Lake was fun in the 50s and 60s. I grew up in the area and swam, hiked, camped, explored and panned for gold all over the area. By the 90s, it became the scene of gang activity, rapes, drugs and murders. I recommend caution if you visit the area.

My mom used to go there as a kid, and so have I... It has definitely changed over the years and it really saddens me!! Where are the tunnels at that you mentioned and morman trails?? Never heard of them!!


The tunnels' entrances have been closed for a long time and the artifacts raided by one of the town's mayors. One entrance was at the bank on E Street. Another was in the old Chinatown area. As for the Mormons, the Mormons traveled over the mountains in covered wagons ...there were no trails for the most part, they simply made their own. If you speak to my friend Ger Brassfield at the Historical Society, he can tell you exactly where the trails were located. The Historical Society is, I believe, at the main library. Mormon Rocks are the wonderfully large rounded boulders seen in Cajon Pass, where the Mormon Trail and railroad meet. Great climbing.


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