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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).

Note: 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, and; (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.

Details: 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. When Lake Powell reaches maximum pool elevation at 3700 feet, Big Drop 3 is the last natural 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). 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. 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: (1) 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 of the principles set forth in the Boulder Canyon Project Act of 1928, which mandated flood control as the primary management priority. This clearly indicates that Reclamation manages Lake Powell for water storage and hydropower, which are the secondary and tertiary management priorities. (2) 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; this shortens the lifespan of this dam. When the sediment load in Lake Powell reaches 50%, the priority objectives of flood control and water storage are compromised. The decaying organic matter is mobilized as well, 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 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 Lake Powell does load the atmosphere with a significant greenhouse gas contribution (Dohrenwend, see presentations below).



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


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

Simmon's Trip Diaries


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.


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 presentation via VIMEO. Tom Martin.


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
Barbara Anne Morra Memorial
Canyon Country Rising Tide
Canyonlands Watershed Council
Celebrating the Grand Canyon
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Returning Rapids Project
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Tom Till Photography
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Upper Green River Network
Uranium Watch
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