B-roll Video: unedited footage of the start of the 2018 High Flow Experiment showing the river outlet tubes being opened at the beginning of the event.
B-roll Video: unedited footage.
The goal of the High Flow Experiment (HFE) is to move sand stored in the river channel and redeposit it to rebuild eroded sandbars and beaches downstream of the Paria River in Grand Canyon National Park. This footage is from a HFE that took place between November 5-10, 2018, when the Department of Interior increased the release of water from Glen Canyon Dam for an HFE of approximately 38,100 cubic ft per second (cfs) for 3 days.
https://www.nps.gov/grca/learn/nature/hfe-23.
Rm 45 before 3/4/2008 (top) & after 3/14/2008 high-flow.
U.S. Geological Survey
On November 5-10, 2018, the Department of Interior will begin increasing the release from Glen Canyon Dam for a high-flow experimental release (HFE) of approximately 38,100 cubic feet per second (cfs) for 3 days. (60 hours)
The goal of the high-flow experiment is to move sand stored in the river channel and redeposit it to rebuild eroded sandbars and beaches downstream of the Paria River in Grand Canyon National Park.
This release follows the science-based Protocol for High-Flow Experimental Releases from Glen Canyon Dam approved in the 2016 Long-Term Experimental and Management Plan Record of Decision for Glen Canyon Dam operations and is a component of the Department’s compliance with the Grand Canyon Protection Act of 1992.
The Grand Canyon Protection Act mandates that Glen Canyon Dam be operated in a manner that protects, mitigates adverse impacts to, and improves the values for which Grand Canyon National Park and Glen Canyon National Recreation Area were established.
Previous experimental releases from Glen Canyon Dam have demonstrated that it is possible to rebuild beaches and sandbars in Grand Canyon via high flows.
2018 Flow Information
Since 1996, releases from Glen Canyon Dam have generally ranged from 8,000 to 25,000 cfs. The increase in flow to approximately 38,100 cfs will change conditions on the Colorado River. Research has shown that some normally difficult rapids decrease in their technical difficulty, and other rapids become more technically challenging at higher flows. River users should exercise caution along the Colorado River through Glen and Grand canyons during the entire week of November 5, 2018.
There are inherent risks associated with recreational activities along the Colorado River corridor through Grand Canyon at all times.
Chart: Shows the 2018 high flow release pattern for Glen Canyon Dam, showing the peak flow between November 5, and November 9.
2018 High flow arrival times at key downstream locations in Grand Canyon National Park.
2018 High Flow Experiment Snapshot
Schedule & Duration
Nov. 5 - 6:00 a.m. begin upramp to powerplant capacity (~23,100 cfs) [7 generation units]
Nov. 5 - 10:00 a.m. open bypass tubes, reach full bypass at 2:00 p.m.
Nov. 8 - 9:00 a.m. end of bypass
Nov. 8 - 3:00 p.m. end of High Flow Experiment
Total duration: 3 days & 10 hours; 2 ½ days at peak release
Ramp Rates
Ramp up: 4,000 cfs/hr from 6,500 - 23,100 cfs, then 3,750 cfs/hr to peak (38,100 cfs)
Ramp down: 1,875 cfs/hr from 38,100 – 23,100 cfs, then 2,500 cfs/hr to 9,000 cfs
High Flow Experiment Release Details
Maximum total release: 38,100 cfs
Powerplant capacity: 23,100 cfs
River outlet tubes: 15,000 cfs
Hydropower generation units available: 7 (one unit off-line for replacement)
River outlet tubes: 4
Releases and Lake Elevation
Releases will range from 6,500 - 9,000 cfs prior to and after the HFE
Lake elevation is projected to decrease by approximately 2 ½ feet during the 5-day experiment
cfs = cubic feet per second
cfs/hr = cubic feet per second per hour
High Flow Experiments (HFE) Below Glen Canyon Dam
are driven by weather, sediment inputs, and other resource conditions, in accordance with the Long-Term Experimental and Management Plan (LTEMP).
DOI will conduct a HFE (HFE) release from Glen Canyon Dam from November 5-8, 2018. This high-flow experiment will include a peak magnitude release of approximately 38,100 cubic feet per second (cfs) for 60 hours (four days including ramping from baseflows to peak release) to move accumulated sediment downstream to help rebuild beaches and sandbars.
Releases from Glen Canyon Dam will begin ramping up to full power plant capacity (approximately 23,100 cfs) on the morning of November 5th. At 10:00 am MST on November 5th, bypass tubes at Glen Canyon Dam will be opened and releases will continue to increase up to full power plant and bypass capacity (approximately 38,100 cfs) by 2:00 pm MST on November 5th. Releases will be maintained at peak release for about two and a half days (60 hours) and then begin ramping back down.
Releases will return to normal operations at about 3:00 pm MST on November 8th. November releases from Glen Canyon Dam prior to and after the HFE are expected to fluctuate between 6,500 cfs and 9,000 cfs.
The decision to conduct this HFE was made after careful consideration of sediment resources as well as potential impacts to other resources downstream of Glen Canyon Dam. Consultation with basin states, American Indian tribes, federal and state agencies, as well as input from Glen Canyon Dam Adaptive Management Program stakeholders, were also critical to the Department of the Interior’s decision to conduct the experiment.
High-flow experiments benefit the Colorado River ecosystem through Glen and Grand Canyons by moving sand in the river channel and re-depositing it in downstream reaches as sandbars and beaches. Those sandbars serve as camping beaches for recreationists, supply sand needed to protect archaeological sites, and provide habitat for wildlife.
River users and backpackers can use these maps to determine which campsites provide the most camping area at high flow.
Camp on Durable Surfaces
Because the river will be carrying a greater volume of water than usual, the high-flow experiment will also change the size and availability of campsites along the Colorado River. Most campsites will be smaller, and some particularly low lying campsites may not be usable. The Grand Canyon Monitoring and Research Center has maps of campsites showing modeled shorelines at 41,000 cfs available online at: https://usgs.maps.arcgis.com/apps/webappviewer/index.html?id=721001c63d91458883340f05c68c55f4
The area available for camping will be smaller at most sites, and river users and backpackers may have to set up tents closer to one another than they would during typical flows. It is important to follow Leave No Trace principles and travel and camp on durable surfaces during this high-flow experiment. Durable surfaces include bare sand above the high flow line, sites where people have previously camped and established trails.
Please do not camp in the pre-dam old high-water zone.
Please Do Not Establish Camps in the Pre-dam Old High-water Zone
which is marked by mesquite, catclaw acacia, and netleaf hackberry on rounded sandy slopes or higher sand terraces.
The old high-water zone is especially fragile because it no longer receives moisture, sand or nutrients from natural annual floods that reached over 100,000 cfs prior to the construction of Glen Canyon Dam and is not replenished by experimental high flows.
Damage to root systems from soil compaction and erosion and to biological soil crusts by camping or social trails may be irreversible due to the extremely fragile nature of the old high-water zone.
"It’s really important that you identify the historic high water line and encourage your entire group to camp below it."
View more chapters of the park's non-commercial river trip orientation video here or on YouTube
River users and backpackers are encouraged to communicate with each other and with river rangers about available campsites in order to protect the canyon's resources and to ensure a quality experience for everyone in the river corridor during the high flow and for those who follow.
Dam tubes open during 2012 high-flow.
Long Term Experimental and Management Plan (LTEMP)
The LTEMP provides a framework for ongoing experiments and management actions, including a framework for using dam operations to release high flows following tributary deposits of new sand into the main channel of the Colorado River. It was developed by the Department of the Interior pursuant to the National Environmental Policy Act based on the best available scientific information developed through the Glen Canyon Dam Adaptive Management Program and other sources of information.
The HFE builds on a wealth of scientific knowledge gained from more than 16 years of extensive scientific research, experimentation, and analysis, including analysis of a series of previous high-flow experimental releases in 1996, 2004, 2008, 2012, 2013, 2014, and 2016. The HFE and other actions in LTEMP are intended to provide additional data essential to inform and refine future management decisions for the management of the Colorado River through 2036.
Humpback chub
This experiment will help scientists and managers better understand whether multiple higher flows created by releasing water from Glen Canyon Dam can be used to rebuild eroded beaches downstream.
Colorado River sandbars within the Grand Canyon provide habitat for wildlife, serve as camping beaches for recreationists, and supply sand needed to protect archaeological sites. High flows may also create backwater areas used by young native fishes, particularly the endangered humpback chub.
