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What’s Under The Lake?

As drought lowers the levels of man made reservoirs all over California amazing things have been popping up in the dry lakebeds. At Folsom Lake the remains of the settlements at Salmon Falls and Mormon Island are visible and at Shasta Lake bridges, train trestles and tunnels will emerge from the depths as waters recede. That got me to thinking on a Mendocino County level and I started digging into another History Mystery I’ll call “What’s Under the Lake?”

Before there was a Lake Mendocino and a Lake Pillsbury (and yes, I know, Pillsbury is over the county line in Lake County) there were villages and people in a wide valley. People lived in contentment on farms and ranches, had a local general store, school, church and post office, and then somebody out to make a quick buck said “Hey, I got this great idea! Let’s build a dam and sell water!”

Lake Pillsbury’s story begins in 1904 when Ukiah residents wanted electrical service 24/7 and a financier named W.W. Van Arsdale formed Eel River Power and Irrigation Co. A diversion dam was started on the Eel River and a mile long tunnel was begun to bring the water through a mountain and into the Russian River drainage. A powerhouse in Potter Valley would provide electricity for Ukiah and irrigation water would be sold. Potter Valley was famous for its watermelons at this time.

map courtesy
map courtesy

Who owned the land needed for this dam and reservoir? Mr. Van Arsdale of course, and today Cape Horn dam impounds Van Arsdale Reservoir and 7.3% of the Eel River watershed (289 sq. miles) is diverted through the eight foot wide tunnel to supplement the Russian River. A new bigger entity, Snow Mountain Water and Power, took over in 1906 and soon the dam, reservoir, turbine generated powerhouse, and Power House Canal into Potter Valley were done.

Cape Horn Dam and the Fish Ladder of Van Arsdale Reservoir [photo courtesy]
Cape Horn Dam and the Fish Ladder of Van Arsdale Reservoir [photo courtesy]
But wait! This set-up only worked from fall into spring when waters ran high. What was needed was an even bigger lake to run the powerhouse year round. The happy folks living in the Gravelly Valley and the village of Hullville began to see life change. Gravelly Valley was, indeed, full of gravel but that didn’t stop Yuki Indians from catching steelhead and gathering basket-making willows there. Elk liked to roll in the mud along the river so it was an excellent native hunting grounds.

James Hull was an early settler before a grizzly bear killed him in 1856. His name was attached to a mountain and a town. The town featured Hunter’s Hotel, a blacksmith, a carpenter’s shop, school, post office and a store. Cattlemen lived in the surrounding lowlands and ran their cattle in the hills. Other folks grazed sheep on Hull Mountain. One local dried deer hides and venison jerky and packed it to the Napa Valley to sell at 50 cents a pound for hides and 25 cents a pound for jerky. He returned to Hullville with onions. Life was good until Snow Mountain Water and Power started buying up the valley and tearing down the town.

Hullville was ¾ mile north of today’s Scott Dam on the north side of the Eel River where Big Squaw Creek enters the lake. In a normal year it is 125’ below the surface of the water. A land feature now called Graveyard Point speaks to where folks in Hullville buried their dead. The coffins were moved to the Upper Lake Cemetery to plots purchased by the power company.

Scott Dam, forming Lake Pillsbury [photo courtesy]
Scott Dam, forming Lake Pillsbury [photo courtesy]
All the Ponderosa Pine in the valley was sawed up in a sawmill built for no other reason than to create lumber to frame the dam. Scott Dam is 96’ high, 515’ long , 10’ thick and it is the oldest combined concrete and earth filled dam still functioning in the state. Built in 1920 the lake was filled by 1922. Bye bye Hullsville. The names Scott and Pillsbury recognize the principle financial investors in these activities. PG&E took over the operation in 1930 including Van Arsdale Reservoir and the Potter Valley project.

And Lake Mendocino? That was a settled area of farms and ranches called Coyote Valley. People grew grapes, hay, grain, hops, apples and alfalfa. Local dairyman milked cows and made cheese and sheep grazed. There were three small schools and a gristmill there. Shodokai Pomo Indians had inhabited the valley for a long, long time.

By 1950 the powers that be decided flood control and recreation would be a great reason to buy out all the land owners, flatten the landscape, spend $6 million and build six million cubic yard earth and rock dam covered with 53,000 tons of concrete and reinforced with 1,400 tons of steel. And, by the way, due to the financing Sonoma County gets most of the water. So that’s what’s under those lakes.

Out of curiosity I wondered if Blue Lakes along Highway 20 between Ukiah and Clear Lake were man made or natural? Well, there’s nothing under Blue Lakes that Mother Nature didn’t put there. Upper Blue Lake is 650’ wide, 180’ deep and 1.2 miles long. Lower Blue Lake is only 6/10 mile long and 25’ deep. A few thousand years ago Mt. Konocti erupted and closed off Cache Creek, the traditional outlet of Clear Lake. The lake overflowed down Clear Creek Canyon to the northwest and dropped the lake level 60’. A few centuries ago a landslide on the slope of Cow Mountain filled up the Clear Creek gorge and backed up the waters to fill Blue Lakes.

To end this History Mystery I’d like to suggest a kid’s picture book. I found it a heartbreakingly sad story. “Letting Swift River Go” is by Jane Yolen and tells the story of a young girl growing up in the safety and comfort of the Swift River Valley of Massachusetts. Then her town is flooded to supply drinking water for Boston 60 miles away and becomes Quabbin Reservoir. The book is a fine lesson in letting go of things we can’t control. Find it in the library or a local independent bookshop.


  1. Jim Armstrong August 7, 2014

    What’s under the lake?
    Some not very important comments:
    It is hard to visualize 96 foot high Scott Dam’s impounding a 125 foot deep lake.

    In spite of the number of delicious stories about how Upper Blue Lake is bottomless and that people who drown there wash up in Point Arena, even 180 feet of depth exagerates its 50 foot maximum.
    The creek that used to drain Clear Lake into the East Fork of the Russian River was, and is, called Cold Creek, not Clear Creek.
    The land slide that closed it is the long grade on Highway 20 right at the Mendocino/Lake county line.
    Claims of the age of the slide range from hundreds to thousands of years.

    • George R. October 4, 2020

      To Jim, and this author,
      Blue Lakes was sounded over 150 years ago and the surveyors then topped out at 300 feet. Since I am a Sailor by trade and depth maps are fairly accurate by the old manual ways, I trust a good sounding over some sonic garbage that might have pinged a fish 180 down. When I was young they submerged a mini submarine to astertain it’s depths and they exceeded that of the Sub. It’s a good thing families like mine have been around for 3 generations to witness these facts, or else ridiculous articles like these would profligate.

      • Harvey Reading October 4, 2020

        You’d love it in Wyoming. Most people here think “their” state produces almost all the beef consumed in the U.S. The cow farmers here actually produce one to two percent of it, if that. If people in Wyoming had to depend on Wyoming ag for their food supply, we’d soon starve.

      • Birdog June 6, 2022

        I concur with George R. The landslide that occurred at Clearlake closed the original outlet of the lake, which originally drain into the Eel/Russian River watershed. It is inaccurate to say the ORIGINAL outlet was via Cache Creek. That became the outlet after the landslide. Don’t be in such a hurry when writing and do the research. Writers have a sacred responsibility to portray events accurately.

  2. Jackie December 12, 2015

    It would be an unique experience to talk, about Pillsbury Lake.

  3. George Cinquini July 18, 2016

    Lake Pillsbury has had a tremendous amount of siltation in the past 20 years or so. The deepest part when last filled was more like 80 feet deep. Back in the 70,s the upper part of the lake on the fork of the Eel was 20-25 feet deep in May. Now it is mud with a small channel.
    Back in the day, we used to actually troll thru split rock with a depth in May about 18-20 feet. All filled in!

  4. Rick Cratty April 22, 2019

    Lived on High Glade, Sanhedrin and Hull mountains as a child. Would have been starting in 1959 through about 64-65. Remember Patterson’s resort. Mac’s… Lived in Winkler’s cabin. Was at Hull’s grave several times, used to get our water from Chipmunk springs.

  5. Jolene Shanahan April 23, 2019

    Yeah I believe all of our Lakes have long histories and Mysteries lurking underneath. Lake Mendocino for instance used to be sacred ground to Native Americans and some say they were also buried there.

  6. Cathie Brians April 29, 2019

    I remember ? through the Valley where Lake Mendocino is!

  7. GARY ESTES May 21, 2019 Born in Lakeport 1947, grew up in Boonville. My Family ancestors homesteaded in and around Covelo from the 1850’s on.
    Our cousin Shannon Barney, is a Mendocino County Sheriff.
    As a kid, we spent a lot of time camping at Lake Pillsbury, swimming and fishing near Pogie Point.
    I remember as a youngster,
    going thru Coyote Valley and then fishing in Lake Mendocino.

  8. Jane Doe February 2, 2023

    I work and live at Lake Pillsbury, the history here is fascinating to say the least. The mountains and surrounding areas are beautiful. I couldn’t imagine life without it! The lake is indeed 125 feet deep at the deepest. This is when the lake is at 100% full! This lake fills Lake Mendocino provides the farmers in Potter Valley with water for there crops, along side of providing power to the town.

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