Celebrate! A Spring High Flow Experiment in Grand Canyon
Last week, the Bureau of Reclamation announced the authorization of a spring High Flow Experiment (HFE) in the Grand Canyon. This is a big deal.
Last week, the Bureau of Reclamation, the federal government agency that oversees and manages operations on the Colorado River, announced the authorization of a spring High Flow Experiment (HFE) in the Grand Canyon. This is a big deal since the last time an HFE was conducted was in the fall of 2018, and the last time a spring HFE was executed was in 2008. And with the Colorado River in the Grand Canyon named as America’s Most Endangered River® just last week, we are thrilled that this action is happening to benefit the ecosystem in the canyon.
What is an HFE?
A High Flow Experiment is in essence a simulated flood being conducted through Glen Canyon dam. In practice, the dam releases a high volume of water, usually through both the hydropower turbines and the bypass tubes, which are lower-elevation tubes through the dam that are usually only used for these short duration floods or in other unique situations (like releasing water during the extreme inflows of 1983) over a limited period of time. HFE’s are extremely important to the management of sand in the canyon and the healthy functioning of the Grand Canyon riparian ecosystem overall.
To set the stage even further, let’s go back to the time before the creation of Glen Canyon Dam. The Colorado River traditionally carried millions and millions of tons of sediment down the river each year. Since Glen Canyon was built, most of that sand has been trapped in the upper reaches of Lake Powell – as flows slow down as the river becomes the lake, the sediment drops out and settles (up near Hite and Halls Crossing and then the San Juan as it enters the lake as well.) The result is that the water coming through Glen Canyon dam is very clear, lacking the traditional sediment that would be carried by the river and maintaining beaches and sandbars and the natural ecological benefits of that silty, sediment-laden water throughout the canyon. This clear water erodes sand from beaches and sandbars, and for decades in the 1970’s and 1980’s was causing real problems with the canyon’s ecology. In the 1990’s and early 2000’s, some experiments were conducted to begin to learn how these floods might act and how they might contribute to sand and other ecological functions within the canyon. Then, in 2016, the Long Term Experimental and Management Plan (LTEMP) was completed and set the guidelines for how and how frequently future HFE’s could be conducted.
Now, the Paria River, which is about 17 miles downstream from Glen Canyon dam (and about a mile below the put-in at Lee’s Ferry) is the main source of sediment into the Grand Canyon. When the Paria River flashes (most commonly during the summer monsoon season) it can deposit tons of sand – sometimes more than a million tons of sand – in a summer. This sand is what can be pushed downstream in an HFE to rebuild beaches and sandbars, and aid in the protection of cultural resources throughout the length of the canyon.
One of the elements within these LTEMP guidelines is how and when these HFE’s may be conducted, and how often the program should try to make them happen. Sadly, they have not happened often enough, and the canyon is really suffering because of it. Since the last HFE in 2018, there have been complications with declining water levels across the basin but felt most acutely in Lake Powell as elevations have declined to record lows. Then in 2021 and 2022, the monsoons delivered abundant sand through the Paria into the Colorado River, but unfortunately also caused a lot of erosion of beaches downstream as these monsoon storms ripped across Grand Canyon and the Colorado Plateau.
Today, we are celebrating the decision by the Bureau of Reclamation to use this opportunity to trigger one of these HFE’s to move the volume of sand currently sitting near the mouth of the Paria to rebuild beaches and sandbars, repair the ecology, and aid the protection of cultural resources downstream.
Reclamation was able to make this decision based on several factors. First, due to the drought operations conducted over the past two years, there is a good amount of water parked in Lake Powell to protect the hydropower infrastructure at Glen Canyon dam that had to be moved downstream sometime this year. Second, the sand is there and the damage to the beaches in the canyon is glaring. Third, the water sitting in Lake Powell right near the dam (in an area above the dam called the “forebay”) is quite cold, which could aid aquatic species downstream. And lastly, there is a window of time where Reclamation and the hydropower providers can shift the timing of some needed maintenance at the dam to free up the opportunity to have all 8 hydropower penstocks and some of the bypass tubes available to actually conduct the high flows through the dam.
This week’s HFE will be pretty dramatic, both visually and scientifically. The flow will begin early Monday morning (April 24) and last into Thursday evening (April 27.) The dam will ramp up releases to 39,500 cubic feet per second (CFS) and hold that for 72 hours straight creating a flood that will flow all the way to Lake Mead over a period of about a week, rebuilding sandbars and beaches along the way (and giving rafters in the canyon an exciting ride!) One additional key point to understand is that HFE’s consume no net loss of water in Lake Powell – after the HFE occurs, Glen Canyon dam will release slightly less water than normal over a period of weeks, in order to make up that amount of water that is shot downstream, yet another benefit in the design in these critically important High Flow Experiments.
Again, we applaud the Bureau of Reclamation, the scientists at USGS’ Grand Canyon Monitoring and Research Center, and everyone else who has been working hard to make one of these HFE’s happen for years. We are looking forward to seeing the great results that will come out of this event very soon.
(To learn more about the Grand Canyon’s history and ecosystem, check out our new story map, Caught in the Middle – we think you will love it!)
2 responses to “Celebrate! A Spring High Flow Experiment in Grand Canyon”
In 2013 we experienced one of these events. We checked with the rangers at Phantom Ranch to try to find about specifics. They said it might happen, but offered no details as to when. We did a layover at Pumpkin Springs and I took photos from very high up. Our boats were tied up about 50 feet down from a large flat rock shaped like a table, that we called sacrifice a virgin rock. We planned to get out early the next day and one member was to get us up. He got up to pee about 2:30 am and everything was OK, then went back to bed. About 4:30 we heard a calm voice saying, “get up people”, I replied we are awake and got out of my tent. Found the kitchen nearby with water flowing about 4″ under a roll-a-table. He had reached out of his tent and felt water, grabbed his tent and sleeping bag and threw them up the bank. I grabbed a tamarisk and fished his tent and sleeping bag out of the water and threw it up the bank. We wound up pulling the boats up 50 feet and tying them to big rocks above “sacrifice a virgin rock”. We lost an ammo can from the kitchen area. The water was way above Pumpkin Springs on the rocks. The water was loaded with whole trees that caused our kayaker to get into a raft to avoid collisions. We had a difficult time going our to Lake Mead the next day or two. The river was littered with water bottles and other rafting paraphernalia. The next year Pete, whose father was an old time surveyor, brought a measuring device that showed a vertical rise of 15 feet at Pumpkin Springs. We later heard that the release of 39.000 plus was accelerated to distract from some political event, but that was never confirmed.
I was thrilled to read about the Spring High-Flow Experiment in the Grand Canyon. It’s heartening to see initiatives that prioritize the health and restoration of our natural waterways. The Grand Canyon is not only a national treasure but also an important ecosystem that deserves our utmost care and attention.
The Spring High-Flow Experiment, with its deliberate release of water from Glen Canyon Dam, serves multiple important purposes. It mimics the natural flooding events that used to occur before the dam’s construction, which helps rejuvenate the ecosystem and restore the ecological processes that rely on periodic high flows.
By simulating these natural flows, the experiment contributes to the improvement of riparian habitat, sediment replenishment, and the overall health of the river ecosystem. It is encouraging to see the collaboration between the Bureau of Reclamation, Grand Canyon National Park, and other stakeholders to undertake such an experiment with the aim of enhancing the long-term ecological integrity of the river.
This type of innovative and science-based approach to river management is crucial for the preservation and restoration of our waterways. It highlights the importance of balancing human water needs with the conservation of our natural ecosystems. The Spring High-Flow Experiment is a testament to the dedication of those involved in ensuring the sustainability of the Grand Canyon and its unique environment.
I commend the efforts of all those involved in planning and executing this experiment. The results and data collected from these initiatives will not only inform future decision-making but also contribute to our understanding of river ecosystems and the role they play in supporting biodiversity, recreation, and cultural heritage.
It is my hope that these collaborative efforts continue, and that more projects like the Spring High-Flow Experiment are undertaken in other river systems across the country. By valuing and protecting our rivers, we can ensure the long-term health and resilience of these precious natural resources.
Thank you for sharing this inspiring news and for your ongoing work in advocating for the protection and restoration of our rivers.