November 2016 High-Flow Experiment

Glen Canyon Dam bypass tubes during 2008 HFE.
Glen Canyon Dam bypass tubes during 2008 HFE.

Quick Links

USGS Campsites map at 41,000 cfs river level
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Glen Canyon Dam 2016 High Flow Update

2016 High-Flow Fact Sheet (721kb PDF)
Flow Information - Camping Tips - High-Flow Protocol

River Mile 45: before & after high flow experiment
Rm 45 before 3/4/2008 (top) & after 3/14/2008 high-flow.

U.S. Geological Survey

On November 7-12, 2016 the Department of Interior will begin increasing the release from Glen Canyon Dam for a high-flow experimental release (HFE) of approximately 36,000 cubic feet per second (cfs) for 4 days. (96 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 established in May 2012 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 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.


Flow Information (download 2016 schedules by clicking on the graphics below)

Since 1996, releases from Glen Canyon Dam have generally ranged from 8,000 to 25,000 cfs. The increase in flow to approximately 37,500 cfs will change conditions on the Colorado River. Research has shown that some normally difficult rapids decrease in their technical difficulty, whereas other rapids become more technically challenging at higher flows.

There are inherent risks associated with recreational activities along the Colorado River corridor through Grand Canyon at all times.

Two high flow experiment charts: on the right Flow arrival times downstream in Grand Canyon (right) release schedule at Glen Canyon Dam may be downloaded as PDF files.
Flow arrival times downstream in Grand Canyon may be downloaded in map form (left). The release schedule at Glen Canyon Dam is also available (right). Click on the graphic(s) above that you would like to download. (PDF files)

2016 High Flow Experiment Snapshot

Schedule & Duration

· Nov. 7 - 6:00 a.m. begin upramp to powerplant capacity (~21,000 cfs) [7 generation units]

· Nov. 7 - 10:00 a.m. open bypass tubes, reach full bypass at 1:00 p.m.

· Nov. 11 - 8:00 p.m. end of bypass

· Total duration: 5 days & 5 hours; 4 days at peak release

Ramp Rates

· Ramp up: 4,000 cfs/hr from 6,500 - 21,000 cfs, then 3,750 cfs/hr to peak (36,000 cfs)

· Ramp down: 1,875 cfs/hr from 36,000 – 21,000 cfs, then 1,500 cfs/hr to 9,000 cfs

HFE Release Details

· Maximum total release: 36,000 cfs

· Powerplant capacity: 21,000 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


This HFE will be the fourth conducted under the Protocol. The timing will begin on the morning of November 7th at 6:00 AM, releases from Glen Canyon Dam will be increased up to full power plant capacity (approximately 21,000 cfs). At 9:00 AM on November 7th, bypass tubes at Glen Canyon Dam will be opened, one every hour, and releases will continue to increase up to full power plant and bypass capacity (approximately 36,000 cfs) by midday on November 7th. Releases will be maintained at peak release for 4 days (96 hours) and then begin ramping back down. Releases will return to normal operations in the early morning hours of November 12th. The entire experiment, including ramping is expected to last nearly 5 full days.

Because of the distances downstream of the dam, increasing flows will reach downstream locations at different times. Flows will arrive at Phantom Ranch (River Mile 87) about 20 hours after release from Glen Canyon Dam, and almost 54 hours after release at Pearce Ferry (River Mile 279). Specific information about flow levels at varying locations within Grand Canyon will be posted before and during the high-flow experiment at Lees Ferry, Phantom Ranch and the Backcountry Information Center.

Current flow at Lees Ferry:

sample campsite map shows projected high flow water level.
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 37,200 cfs available online at

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 especially 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.

old high-water vegetation zone.
Please do not camp in the pre-dam old high-water zone.

Camps should not be established 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.

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54 seconds

"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.

Looking down from Glen Canyon dam during 2012 HFE with tubes open.
Dam tubes open during 2012 high-flow.

High-Flow Protocol

The high-flow protocol is 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 protocol 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 and 2014. The protocol is intended to provide additional data essential to inform and refine future management decisions for the management of the Colorado River through 2020.

Several humpback chub swimming in shallow water. Sunlight filtering down creates bright spots.
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.


Glen Canyon Dam bypass tubes during 2008 HFE.
Glen Canyon Dam bypass tubes during 2008 HFE.

Quick Links

USGS Campsites map at 41,000 cfs river level
(This page may take a while to load)

Glen Canyon Dam 2016 High Flow Update

2016 High-Flow Fact Sheet (721kb PDF)
Flow Information - Camping Tips - High-Flow Protocol

Last updated: November 2, 2016

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Mailing Address:

PO Box 129
Grand Canyon, AZ 86023


(928) 638-7888

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