An underwater forest reveals the story of a historic megadrought

  • Ancient trees like this one preserved in the waters of Fallen Leaf Lake in California are helping scientists piece together the region's drought patterns.

    Graham Kent
  • Ancient trees like this one preserved in the waters of Fallen Leaf Lake in California are helping scientists piece together the region's drought patterns.

    Phil Caterino
 

A curved tree saw in his gloved hand, a scuba tank on his back, Phil Caterino worked quickly to slice through a pine branch 100 feet below the surface of a small tarn south of Lake Tahoe. Bubbles streamed from the regulator in his mouth, rising through the blue alpine water and green flecks of algae in Fallen Leaf Lake. That autumn day in 1997, Caterino briefly considered what would happen if he accidentally nicked the air hose running to his mouthpiece, or cut his orange dry suit, letting the 39-degree water rush in. "I'd be at the bottom of the lake, dead in about five minutes," he mused.

Having dived some 400 high-altitude lakes over the course of 30 years -- often reciting a protective Washoe prayer beforehand -- Caterino, director of the Lake Tahoe-based environmental nonprofit Alpengroup, doesn't shy away from occupational hazards. He surfaced a few minutes later, branch in hand. Even though the tree it came from had been stewing underwater for 800 years, it still smelled pungently of sap.

This botanic relic is one of several medieval trees, ranging from 68 to 100 feet tall, standing upright at the bottom of the lake. They grew during a 200-year megadrought in the Sierra Nevada between the 9th and 12th centuries, when precipitation in the area fell to less than 60 percent of the average between 1969 and 1992. Fallen Leaf Lake dropped about 150 to 200 feet below its current level, allowing the trees to grow above the lower shoreline. In the wetter years that followed, the lake quickly refilled, drowning the trees and sealing them in a liquid catacomb, safe from insects and fungi in the deep, low-oxygen water. There are also three older trees, which drowned between 18 and 35 centuries ago, standing upright on the lake floor, which suggests that severe droughts struck even further back in time.

The medieval trees' existence adds to the body of research documenting the Sierra Nevada's past megadroughts. Researchers have found stumps of long-dead trees in rivers, lakes and marshes in the region, indicating not one, but two medieval megadroughts -- the other lasting about 140 years in the 13th and 14th centuries, dwarfing the 20th century's Dust Bowl. Such megadroughts are a frightening prospect, and it's possible they could strike again.

John Kleppe, a professor emeritus at the University of Nevada-Reno who owns a lakeside home on Fallen Leaf, accidentally discovered the mysterious climatic archive. For 15 years, his fishing lures bumped against an unknown something in the deeps. "It looked like a fish strike," says Kleppe. "The pole just bent down. I never snagged and never caught anything." Curious, he finally asked Caterino to investigate.

Once Caterino found the first tree, Kleppe began combing the lake for more. He rigged a weighted 150-foot line between the undersides of two boats and slowly scoured the lake. Whenever he hooked a tree, he marked its location and later sent down a camera mounted on a propeller-driven Remotely Operated Underwater Vehicle, or ROV, with a pincer in the front for grabbing samples, and lights mounted on its side. Its footage showed the otherworldly trees with their roots supported by rocks and sediment buildup.

Graham Kent, director of the Nevada Seismological Laboratory, witnessed a surreal underwater scene first-hand from a two-person submersible in 2009. Peering out of the glass orb that encases pilot and passenger, Kent saw lures and fishing lines dangling like tinsel from tree branches, along with tiny single-celled organisms grouped into colonies resembling jellyfish, catching the subsurface light. "It was a bizarre Christmas-tree effect," he recalls. "I was just waiting for Rudolph the Red-Nosed Reindeer to come flying in."

The reindeer failed to appear, but Kent used torpedo-shaped sonar imaging equipment controlled from a boat to rule out the possibility that an earthquake had cracked the lake's bottom, causing water to leak out, or that a landslide had sent the trees tumbling into the lake. The sonar equipment not only helped confirm that drought caused the lake's waters to plummet, it also revealed the ancient shoreline from the past dry spell. His colleagues used tree-ring analysis and radiocarbon dating to calculate the trees' age. This, coupled with a model of how quickly water in the lake evaporates and leaks out into its neighbor, Lake Tahoe, gave the researchers a full picture of the drought's severity and timing.

Knowing that megadroughts hit the Sierra Nevada in the past puts recent dry and wet spells into perspective. In California, the urban and agricultural infrastructure is built on the assumption that winter precipitation for the last 160 years is representative of "everything Mother Nature has to throw at us," says Scott Stine, a professor emeritus at California State University, East Bay, who published a seminal paper in 1994 on megadroughts.

"If we take just a slightly longer view of things, we see that this whole urban and agricultural infrastructure, so dependent on water, is something of a chimera. It is not sustainable in the long term."

High Country News Classifieds
  • EXECUTIVE DIRECTOR
    The Public Lands Foundation, a non-profit organization supporting the multiple-use management of public lands managed by the Bureau of Land Management, seeks an experienced leader...
  • CLIMATE JUSTICE FELLOW
    High Country News, an award-winning magazine covering the communities and environment of the Western United States, seeks applicants for a climate justice fellowship. The fellowship...
  • YELLOWSTONE TREASURES: THE TRAVELER'S COMPANION TO THE NATIONAL PARK
    Dreaming of a trip to Yellowstone Park? This book makes you the tour guide for your group! Janet Chapple shares plenty of history anecdotes and...
  • OLIVERBRANCH CONSULTING
    Non-Profit Management Professional specializing in Transitional Leadership, Strategic Collaborations, Communications and Grant Management/Writing.
  • SAGE GROUSE CCAA COORDINATOR
    The Powder Basin Watershed Council, headquartered in Baker City, Oregon, seeks a full-time Sage Grouse CCAA Coordinator. This position is part of a collaborative effort...
  • MARKETING COMMUNICATIONS MANAGER
    High Country News, an award-winning media organization covering the communities and environment of the Western United States, seeks a Marketing Communications Manager to join our...
  • EXECUTIVE DIRECTOR - OKANOGAN LAND TRUST
    Executive Director, Okanogan Land Trust Position Announcement Do you enjoy rural living, wild places, family farms, challenging politics, and big conservation opportunities? Do you have...
  • GREAT VIEWS, SMALL FOOTPRINT
    Close to town but with a secluded feel, this eco-friendly home includes solar panels, a graywater reuse system, tankless hot water, solar tubes, and rainwater...
  • EXECUTIVE DIRECTOR
    Powder River Basin Resource Council, a progressive non-profit conservation organization based in Sheridan, Wyoming, seeks an Executive Director, preferably with grassroots organizing experience, excellent communication...
  • COMMUNITY ORGANIZER- NORTHERN PLAINS RESOURCE COUNCIL
    Organize with Northern Plains Resource Council to protect Montana's water quality, family farms and ranches, & unique quality of life. Starts $35.5k. Apply now- northernplains.org/careers
  • BEAUTIFUL, AUTHENTIC LIVE YULE LOG CENTERPIECE
    - beautiful 12" yule log made from holly wood, live fragrant firs, rich green and white holly, pinecones and red berries. $78 includes shipping. Our...
  • CRAZY HORSE MEMORIAL DIRECTOR OF PROGRAMS FOR THE INDIAN UNIVERSITY OF NORTH AMERICA
    Crazy Horse Memorial, in the Black Hills of South Dakota, is currently accepting applications and nominations for the Director of Programs for The Indian University...
  • CRAZY HORSE MEMORIAL® MANAGER OF RESIDENCE LIFE FOR THE INDIAN UNIVERSITY OF NORTH AMERICA®
    Crazy Horse Memorial is currently accepting applications for the Manager of Residence Life for The Indian University of North America. This position is responsible for...
  • EXECUTIVE DIRECTOR
    Are you an art lover who dreams of living in the mountains? Is fundraising second nature to you? Do you have experience managing creative people?...
  • EDITOR-IN-CHIEF
    High Country News, an award-winning media organization covering the communities and environment of the Western United States, seeks an Editor-In-Chief to join our senior team...
  • LENDER OWNED FIX & FLIP
    2 houses on 37+ acres. Gated subdivision, Penrose Colorado. $400k. Possible lender financing. Bob Kunkler Brokers Welcome.
  • HISTORIC LODGE AND RESTAURANT - FULLY EQUIPPED
    Built in 1901, The Crazy Mountain Inn has 11 guest rooms in a town-center building on 7 city lots (.58 acres). The inn and restaurant...
  • POLLINATOR OASIS
    Seeking an experienced, hardworking partner to help restore a desert watershed/wetland while also creating a pollinator oasis at the mouth of an upland canyon. Compensation:...
  • ELLIE SAYS IT'S SAFE! A GUIDE DOG'S JOURNEY THROUGH LIFE
    by Don Hagedorn. A story of how lives of the visually impaired are improved through the love and courage of guide dogs. Available on Amazon.
  • COMING TO TUCSON?
    Popular vacation house, furnished, 2 bed/1 bath, yard, dog-friendly. Lee at [email protected] or 520-791-9246.