Lake Mead watch: At lowest levels since 1937

 

For almost two decades, the white band of mineral deposits circling Arizona’s Lake Mead like a bathtub ring, has grown steadily taller, a sign that America’s largest manmade water source is in deep trouble. This week it fell to its lowest level since 1937, when Hoover Dam was completed and the reservoir filled.

395742119_89e6d6a97f_z.jpg
The white bathtub ring around Lake Mead shows how much water levels have fallen in recent years. Credit: Chris Richards/Flickr.

The record-setting mark of 1,082 feet  is just seven feet shy of the level that would spur more strict water rationing. It's the latest indication of  a worrisome trend affecting the Colorado River Basin: an unholy mix of drought exacerbated by climate change and increasing water use that’s leaving 40 million people who depend on the river for their drinking water and an entire region of water dependent industries thirstier than ever.

Water in Lake Mead has been dropping steadily since 1998, the last year in which the reservoir was near capacity. Currently it’s just 39 percent full, a number that the Bureau of Reclamation predicts will continue to drop.

There’s a 50 percent chance that by 2017, water levels in Lake Mead will have fallen below 1,075 feet, the amount needed to trigger water use restrictions for Arizona and Nevada. Those two states will be rationed first, out of the seven that share Colorado River water.

So you’d think that the seven states that rely on the Colorado River would be working frantically to reduce the amount of water they take out of the river.  Well, not quite. Despite diminishing river flows and climate change models that indicate more intense and frequent dry spells, a growing population throughout the West mean most of the cities and water districts in Colorado, Wyoming, Utah, New Mexico and Arizona are planning to use more Colorado River water, not less.


Map from Bureau of Land Management

Many states are trying to get the last legally allowed drop of water out of the river before others do. Under the 1922 agreement, negotiated by the seven Colorado River Basin states, Colorado, Utah, New Mexico, and Wyoming are entitled to 7.5 million acre-feet per year. Currently, however, average annual use is only 4.6 million acre-feet, which means the four upper states have legal authority to increase their Colorado River diversions by as much as 2.9 million acre-feet. And the growing population makes it increasingly likely they'll take advantage of that authority.

The trouble is, the agreed-upon allocations stem from a wetter-than-average period and forecasts made nearly a century ago.

“Everyone agrees that when the Compact was signed in 1922 they were basing the Upper Basin and lower allocations on the data they had which came from years of high water levels from good snowpack,” said Rose Davis, a Bureau spokeswoman in Boulder City, Nevada. “They do acknowledge the river was over-allocated.”

River flows over the last century averaged 15 million acre-feet annually. But a 2012 Bureau of Reclamation study found that by 2060 flows will drop to 13.7 million acre-feet, leading to a potential 3.2 million acre-feet gap in supply and demand (one acre-foot equals the amount of water needed to cover an acre of land with one foot of water).

Nevertheless, Davis cautioned that despite the dire predictions for water levels, the projections are highly variable. “We could get a lot of snow in the next 2 years which could change things for the better,” she said.

But cities like Las Vegas – which draws 90 percent of its drinking water from Lake Mead – aren’t taking any chances. With one of the city's two intake pipes at risk of being exposed, the Southern Nevada Water Authority is spending at least $829 million to dig a 20-foot-tall, 3-mile-long tunnel to go deeper into the reservoir.

And there’s the recently launched Colorado River System Conservation Program, a collaborative effort among the four largest water districts that rely on the Colorado River. It will pay farmers, industries, and municipalities to reduce their water consumption.

On July 8, Nevada State Senator Tick Segerbloom introduced a bill calling for an independent audit of the Bureau of Reclamation’s strategies for managing the Colorado River and criticized the Bureau for not addressing threats to the river’s water levels that scientists have been warning about for years.

As the circle of white around the walls of Lake Mead grows deeper and the river that feeds the reservoir shrinks, no one can afford to ignore the underlying problem: we are draining more water out of the system than the river is putting in.

For more HCN coverage of the Colorado River, start with "How Low Will It Go" and "New Hope for the Delta" by Matt Jenkins. Sarah Tory is an editorial intern at High Country News. She tweets @tory_sarah.

High Country News Classifieds
  • UNIQUE, ENERGY-EFFICIENT HOME ON ACREAGE NEAR MOSCOW, IDAHO
    Custom-built energy-efficient 3000 sqft two-story 3BR home, 900 sqft 1 BR accessory cottage above 2-car garage and large shop. Large horse barn. $1,200,000. See online...
  • OUTDOOR ADVENTURE BUSINESS FOR SALE
    Missoula Outdoor Learning Adventures (MOLA) - established and profitable outdoor adventure & education business in Missoula, Montana. Summer camp, raft & climb guide, teen travel,...
  • OJO SARCO FARM/HOME
    A wonderful country setting for a farm/work 1350s.f. frame home plus 1000 studio/workshop. 5 acres w fruit trees, an irrigation well, pasture and a small...
  • STEWARDSHIP COORDINATOR
    Join Skagit Land Trust (the Trust), a not-for-profit conservation organization based in Mount Vernon, Washington, and help protect land for people and wildlife. Skagit Land...
  • 2022 SEASONAL SCIENCE EDUCATOR
    The Mount St. Helens Institute Science Educator supports our science education and rental programs including day and overnight programs for youth ages 6-18, their families...
  • POLICY DIRECTOR
    Heart of the Rockies Initiative is seeking a Policy Director to lead and define policy efforts to advance our mission to keep working lands and...
  • CHIEF FINANCIAL OFFICER
    Self-Help Enterprises seeks an experienced and strategic CFO
  • CONSERVATION SPECIALIST - LAND PROTECTION FOCUS
    View full job description and how to apply at
  • RIVER EDUCATOR & GUIDE
    River Educator & Guide River Educator & Guide (Trip Leader) Non-exempt, Seasonal Position: Full-time OR part-time (early April through October; may be flexible with start/end...
  • LAND AND WATER CONSERVATION DIRECTOR
    The Land and Water Conservation Director is a full-time salaried position with the Mountain Area Land Trust in Evergreen, CO. The successful candidate will have...
  • FOOD SYSTEMS ENVIRONMENTAL FELLOWSHIP
    If you were to design a sustainable society from the ground up, it would look nothing like the contemporary United States. But what would it...
  • EXECUTIVE DIRECTOR
    The Rio Grande Headwaters Land Trust (RiGHT) is seeking an Executive Director who will lead RiGHT toward a future of continued high conservation impact, organizational...
  • COMMUNITY ORGANIZER
    Help protect Montana's water quality, family farms and ranches, & unique quality of life. Work hard, meet good people, make the world a better place!...
  • VERDE RIVER PROJECTS TECHNICIAN
    The Verde River Projects Technician (VRPT) provides technical assistance to Verde River Program staff in implementation of the Verde River Streamflow Monitoring Protocol. This consist...
  • 8 FIELD PROJECT SPECIALISTS (POSITION FORMERLY TITLED TRAIL CREW TECHNICAL ADVISOR)
    Are you passionate about environmental conservation and connecting people to the outdoors? The Pacific Crest Trail Association (PCTA) is looking for someone with outdoor leadership...
  • SOUTHWEST REWILDING ADVOCATE
    WildEarth Guardians is seeking a full-time advocate in our Wild Places Program to advance a new paradigm of forest management and protection based on the...
  • NEW BOOK:
    True Wildlife Tales From Boy to Man. Finding my voice to save wildlife in the Apache spirit. 365+ vivid colorful pictures. Buy on Amazon/John Wachholz
  • CHIEF OPERATIONS OFFICER
    with Rural Community Assistance Corporation. Apply here: https://www.marcumllp.com/executive-search/chief-operations-officer-rcac
  • CARPENTER WANTED
    CARPENTER WANTED. Come to Ketchikan and check out the Rainforest on the coast, Hike the shorelines, hug the big trees, watch deer in the muskeg...
  • WATER PROJECT MANAGER, UPPER SAN PEDRO (ARIZONA)
    Based in Tucson or Sierra Vista, AZ., the Upper San Pedro Project Manager develops, manages, and advances freshwater conservation programs, plans, and methods focusing on...