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Citizen and Professional Science in Glen Canyon National Recreation Area

November 01, 2021
by John S. Weisheit

A HISTORY of citizen and professional science related to significant low reservoir levels at Glen Canyon National Recreation Area (Lake Powell).

Glen Canyon National Recreation Area (GCNRA) includes:
(1) The lower half of Cataract Canyon below Big Drop Two, which is also the end of Canyonlands National Park (CANY).
(2) All of Narrow Canyon beginning at the end of Mille Crag Bend, or when you can see the Henry Mountains.
(3) All of Glen Canyon beginning at the mouth of the Dirty Devil River and ending at the mouth of the Paria River near Lee's Ferry, Arizona.

Geographic Details:
(1)The northern boundary of Glen Canyon National Recreation Area (GCNRA) begins at elevation 3715 feet on the Colorado River in the middle of Cataract Canyon. This elevation corresponds with the height of the concrete parapets on the crest of Glen Canyon Dam. This elevation occurs at a rapid known as Big Drop 2.
(2) When Lake Powell reaches maximum pool elevation at 3700 feet, Big Drop 3 is the last unaltered rapid in Cataract Canyon. The southern boundary of GCNRA occurs below Glen Canyon Dam at the mouth of the Paria River in northern Arizona (Lee's Ferry).
(3) This location near Lee's Ferry is also the northern boundary of Grand Canyon National Park and the beginning of Marble Canyon. The Grand Canyon Sub-province begins at the mouth of the Little Colorado River. The lands on the east side (river left and pointed downstream) of the Colorado River (or reservoir), between the mouth of the San Juan River to the mouth of the Little Colorado River, are the lands of the Navajo Nation.
(4) All of this country, including Marble Canyon, is in the Canyonlands Sub-province of the Greater Colorado Plateau (Hunt, 1956).


After observing 60-years of reservoir management at Lake Powell, we present the following contradictions that have emerged:

(1) The original name was Glen Canyon Reservoir and the filling criteria began in March of 1963.  The name was formally changed to Lake Powell when Lady Bird Johnson dedicated the facility for the people of the 50 United States in 1966. It required 17-years to finally fill Lake Powell, which occurred in Year 1980. The decades of the 1980s and 1990s were significantly wetter than previous decades, and interupted by a four-year dry cycle between 1989 and 1992. By 1992 the reservoir capacity had dropped to 50%. This condition occurred again in 2002 and, by March of 2005, the capacity dropped to 35%, which then launced the development of an Environmental Impact Statement called "Shortage Criteria" and finalized as 2007 Interim Guidleines.

(2) A brim full reservoir, as occurred from 1983 to 1988 and from 1995 to 2000, essentially means there was no flood control capacity in the Colorado River Basin. This is a variance to the principles set forth in the Boulder Canyon Project Act of 1928, which mandated flood control as the primary management priority. It must be understood that if something goes wrong with the structural integrity of Glen Canyon Dam, and it becomes necessary to vacate the reservoir of water as quickly as possible to avoid a catastrophe, that it would take about 12 months to complete the evacuation process. This means that dam safety is dependent upon perfect performance at all times and under all conditions. Yet, no human endeavor has ever matched the power of nature. 

This clearly indicates that Reclamation manages Lake Powell for water storage and hydropower, which are the secondary and tertiary management priorities. This is why the snowmelt of 1983 became an emergency situation at Glen Canyon Dam and caused by a reluctance to vacate the reservoir to safely accommodate inflows of 111,500 cfs (Burgi, 1984) and a 4-month snow melt volume of 15 million acre-feet. It is now reasonable to conclude that, had the volume been a five-month snow melt of 30 million acre-feet, as in 1884, Glen Canyon Dam would have been breached by the Colorado River (Swain, 2002).

(3) One of the incidental purposes of Lake Powell is to settle and store entrained sediment and organic detritus. When Lake Powell elevations are low the stored sediment and organic detritus is mobilized by the Colorado River and carried further downstream toward Glen Canyon Dam (Pratson, 2008); this shortens the lifespan of this dam. This includes the stored sediment in the 125 side canyons, many of which are in close proximity of Glen Canyon Dam, such a Wahweap and Antelope canyons. When the sediment load in Lake Powell reaches 50%, the priority objectives of flood control and water storage are compromised (USGS, 1960). Or, when sediment reaches the elevation of the outlet tubes on the front face of Glen Canyon Dam, a dredging program must begin (Schultz, 1961). A reservoir losing storage capacity to sediment fill is the same as depleting the capacity of an aquifer to zero. You end up with nothing.

(4) Erosion by a flowing Colorado River over exposed reservoir sediment mobilizes decaying organic matter and this becomes a water quality issue, especially for the aquatic species of the reservoir, and the aquatic species below Glen Canyon Dam. This would also be true for Hoover Dam and Lake Mead. The decay process of the organics decreases oxygen levels in the water column of the reservoir, and the odors of hydrogen sulfide emissions are most unpleasant, and the emissions of raw methane gas (odorless) from Lakes Powell and Mead does load the atmosphere with a significant greenhouse gas contribution (Dohrenwend, see presentations below). See: Hydropower is likely to have no future on the Colorado. OTC.









1950 to 1993: Kent Frost; professional land and river guide.


1952 to 1956: George Simmons (USGS employee) and several colleagues.

MAPS: USGS; 1923; baseline data and observations before reservoir inundation

Simmon's Trip Diaries


UTAH: Ownership and Natural Resource Maps; Circa 1975.

Glen Canyon National Recreation Area (Lake Powell)

Utah BLM: Circa 2017


1992 to 2004: Dr. Robert H. Webb (USGS), Dr. Jayne Belnap (USGS), and John Weisheit (professional guide).
Repeat photography and data when reservoir was nealy full in the 1990s.
Cataract Canyon: An Environmental and Human History of the Rivers in Canyonlands. University of Utah Press; 2004.



2002 to 2006: Dr. John Dohrenwend (USGS) & John Weisheit
Original photos; repeat photography and presentations.


2017 to present: The Returning Rapids Project; Mike DeHoff (Principal Investigator) and colleagues


2021 to present: Glen Canyon Rejuvenation Project; Dr. Dan McCool and colleagues

Aerial Photos: Light Hawk Overflight of September 10, 2021.


2021 to the present: Tom Martin (River Runners for Wilderness) and John Weisheit (Living Rivers & Colorado Riverkeeper).

Dirty Devil Boat Ramp to Bullfrog Creek Boat Ramp

  • Trip dates: September and October of 2021
  • By staff and volunteers for the fiscally sponsored projects of Living Rivers: River Runners for Wilderness and Colorado Riverkeeper.
  • CLICK HERE to view this repeat photograpjy presentation via VIMEO. Tom Martin.
  • Note: Stay tuned for more repeat photgraphy
Repeat photography boat trip; October 10 to 14, 2021; reservoir elevation 3545 feet.
Note: Portfolios; files reduced; takes awhile to download.

The Repeat Photos


Stay tuned for a more detailed narratives that will include landscape and aerial photos.



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Dam Operations
Public Notices


Back of Beyond Books
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Canyon Country Rising Tide
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Celebrating the Grand Canyon
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Las Vegas Water Defender
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People's Energy Movement
Resource Renewal Institute
Returning Rapids Project
River Runners for Wilderness
Save The Colorado
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Sheep Mountain Alliance
Steaming Bean Coffee Company
Tom Till Photography
Upper Colorado River Watershed Group
Upper Green River Network
Uranium Watch
Utah Rivers Council
Utah Tar Sands Resistance
Wabi Sabi
Waterkeeper Alliance

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