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Part One: Citizen and Professional Science in Glen Canyon National Recreation Area

November 01, 2022
by John S. Weisheit

Photo above from Lake Powell: Jewel of the Colorado. Floyd Dominy; DOI, 1965.

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PROJECT PROGRAMMING: Lake Powell Sedimentation


STREAM GAGE: above the Dirty Devil River
Colorado River Bridge by US Geological Survey
Measures daily flow volume and river elevation. A river flowing on reservoir sediment (Lake Powell)
  • https://waterdata.usgs.gov/monitoring-location/09328990/#parameterCode=00065&period=P7D
  • January 1, 1963 - River bed elevation was about 3,450 feet (before the filling of Lake Powell).
  • January 1, 2003 - Reservoir sediment elevation was about 3,620 feet.
  • March 29, 2023 - River elevation at 3,580 feet.
  • Note: The weight of reservoir sediment and water does compress the matrix of sand, silt, clay and organic drift (leaf litter). When reservoir water evacuates (evaporation and human consumption), the exposed sediment will begin to dewater, fracture, subside, and will be covered by native and non-native vegetation very quickly. As the river begins to incise into the sediment, there are lateral slump features that launch into the river without warning; these slump blocks become islands of mud, until the velocity currents dissolve them. This remobilized sediment will sink to the bottom when the river reaches the stilled water of Lake Powell (currently uppermost Good Hope Bay). We have witnessed the delta advance into Lake Powell at a rate of 100-feet per day. This natural remobilization of reservoir sediment is happening in every side canyon and river tributary at various magnitudes throughout Glen Canyon National Recreation Area.
  • 2022 - Sedimentary record of annual-decadal timescale reservoir dynamics: Anthropogenic stratigraphy Lake Powell, Utah, USA. Johnson.
  • Returning Rapids Project. Dehoff.
  • 2023 - Spring Report. Returning Rapids Project; Dehoff.

Bureau of Reclamation


Salt Lake Tribune
High Country News
Returning Rapids Project

Utah Guides and Outfitters

Colorado Plateau River Guides



Soon to arrive
  • The 1871 photos of Powell Expedition
  • The 1872 photos of Wheeler Expedition
From the diary of John Wesley Powell at the beginning of Glen Canyon: July 28, 1869...we discover the mouth of a stream which enters from the right. Into this our little boat is turned. The water is exceedingly muddy and has an unpleasant odor. One of the men in the boat following, seeing what we have done, shouts to Dunn and asks whether it is a trout stream. Dunn replies, much disgusted, that it is "a dirty devil"...
Glen Canyon National Recreation Area (GCNRA)

Dirty Devil River Primitive Boat Ramp (sometimes called North Wash) and near (opposite shore) the defunct Hite Marina facility (defunct as of 2003).

  • August, 2021 - Drawing of Dirty Devil Boat Ramp.
  • Note: The park service does not give reports on conditions at the Dirty Devil River Primitive Boat Ramp.
  • Note: the creep of the lateral slumping toward the river is increasing; we think this boat ramp is compromised and will cause serious injuries.
  • As of June 19, 2022 the upstream ramp slumped into the river, leaving a 10-foot escarpment of reservoir sediment. The ramp has since been modified a bit downstream, which has some bedrock features for stability. Video. mov.
  • As of March 2023, the Colorado River has removed about 40 feet of sediment since 2019 and this rate of removal continues. We expect the ramp to be totally unusable by the summer of 2023, and it is also possible that this sediment removal may encounter bedrock features and create either a bedrock rapid or a bedrock waterfall.

Citizen Monitoring @ Dirty Devil Take-out


View or download photo portfolios (these pdf photo compilations are large files)
Courtesy of John Weisheit

March of 2022

March of 2023


At reservoir elevation 3530 feet   
  • Current conditions as of October 2022 between Dirty Devil Take-out and Farley Canyon: There is a knick point one mile above Farley Canyon, and eroding headwardly (the opposite direction of river flow) at a rate of about 25 feet per day. The river incision into the mud and detritus layers of Powell Reservoir creates islands that dewater and then eventually slump and/or slide into the deepening incision.
  • The magnitude of these slump features can resemble an Arctic glacier crumbling into the ocean, or consist of large sections (typically 25 feet by 100 feet) that launch themselves sideways into the Colorado River at random moments (can be dangerous).
  • When the gains of entrained sediment reach the still waters of Reservoir Powell, the load drops into the deep water column of the reservoir, and presently located at The Horn, a couple miles above Good Hope Bay. This “delta” feature advances into the reservoir at an average annual rate of about 100 feet per day; especially during a vigourous monsoon season, as occured in the summer/fall of 2022.

Matching photos from the Nielsen Collection near Farley, White and Trachyte canyons




Glen Canyon National Recreation Area (GCNRA)


A HISTORY: 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.
(4) The NRA was established by Congress in 1972.

The Filling Criteria for Glen Canyon Reservoir (Lake Powell)

Publications during the filling criteria for Lake Powell

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. The southern boundary of GCNRA occurs below Glen Canyon Dam at the mouth of the Paria River in northern Arizona (Lee's Ferry).
(2) The NRA boundary on the San Juan River begins after the river meanders called the "Goosenecks" and near Mexican Hat, Utah. The right side of the river is the NRA and the left side of the river is Navajo Nation. Visitation on Navajo lands requires a special use permit.
(3) When Lake Powell reaches maximum pool elevation at 3700 feet (design specifications), Big Drop 3 is the last natural rapid in Cataract Canyon. The next rapid, which is Rapid #24, was underwater after various snow melts in 1980s.
(4) 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.
(5) 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 interrupted 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 launched 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 1998, essentially means there was no flood control capacity in the Colorado River Basin, See: Vandivere et al., 1984 & Floods Reveal Water Policy Chaos; HCN, 1983. This is a variance to the principles set forth in the Boulder Canyon Project Act of 1928 (BCPA), 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 to 16 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 can possibly control the extremes of nature.

Glen Canyon Dam will fail someday and, potentially, 27 million acre-feet of water, sediment and rotting organic materials will burst through Grand Canyon and into Lake Mead and then over the crest of Hoover Dam. The majority of the discharge, beginning with emergency spillway releases at Hoover Dam, will flow into the structural depression known as the Salton Through, rather than the Gulf of California. If dam failure at Glen Canyon Dam occurs, the discharge of the outburst flood will overtop Hoover Dam with a column of water that would be, 70-feet thick (see Lantham, 1998). Hoover Dam will either fail too, or suffer damages so severe that that it will become completely inoperable. Incidentally, the water storage capacity of the Salton Trough is 405 million acre-feet (Lake Mead times 14). The overflow point is north of Mexicali, Mexico.

This clearly indicates that Reclamation does not manage Lake Powell for flood control and dam safety. Rather, the priority operating criteria for Lake Powell is to maximize water storage and hydropower production, which are the secondary and tertiary management priorities of the BCPA. 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). Reservoir-based hydropower is not clean, it is not safe, and it is not sustainable. See: Hydropower is likely to have no future on the Colorado. OTC.


LAKE CAHUILLA: The Colorado River Basin's natural lake since time immemorial
Large Colorado River floods filling the Salton Trough (Salton Sea). An ephemeral and prehistoric natural lake that has a greater volume than Lake Powell by 15 times.


End of Part One


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