Sand Bars in Grand Canyon, April 2003;
Some Observations on Adaptive Management Actions

Background on the Experimental Flow Program:
What’s the problem? (2001)
Long term monitoring of fine sediment and endangered fish by the Grand Canyon Monitoring and Research Center (gcmrc) was shown both to be in severe decline. These two ecosystem resources are widely held as keystone elements in the beleaguered post-dam river ecosystem.
What did we do? (January 2002)
The Adaptive Management Work Group (amwg) requested Interior secretary Gail Norton to design experimental releases from Glen Canyon dam that would mitigate loss of sediment and endangered fish. To accomplish this objective, Bureau of Reclamation (bor) followed procedures of the Adaptive Management Program as mandated by the Glen Canyon Dam eis and Record of Decision (rod). The plan was to satisfy congressional intent as expressed in the Grand Canyon Protection Act of 1992 (gcpa): to operate the dam to “preserve, mitigate adverse impacts to, and improve the values for which Grand Canyon National Park and Glen Canyon National Recreation Area were created” (sect. 1804, gcpa).
How did this happen? (January 2002)
We drafted and pushed a motion through amwg to reverse the decline of these important natural resources. The motion was called the “sediment conservation experiment”. It was intended to mitigate long term sediment loss, while respecting the need to save the endangered Humpback chub. An experimental design was then developed by gcmrc with comments taken from all 24 stakeholders. It included a plan for flood release(s) from the dam to rebuild sand bars when tributary sediment input to Marble Canyon reached a specified trigger level.
One element of the proposed experiment includes high daily fluctuations, January to March, over multiple years. The hypothesis proposes that disrupting spawning habitat of the competitive/predatory(?) non-native fishes in the Lees Ferry reach would enhance habitat for the endangered native fish downstream.
Sediment scientists predicted that the proposed high daily fluctuations would quadruple sediment transport out of Grand Canyon to Lake Mead above normal rod flows. Some of us on the amwg raised concerns about predicted erosion of sediment, but these were not incorporated into the experimental design by gcmrc and bor, which increasingly changed focus to allocating resources to conservation of native fish.
Where are we now? (April 2003)
Last summer, an Environmental Assessment was conducted by bor with public input and then approved by the secretary with a Finding of No
Significant Impact (fonsi, December 2002, see http://www.uc.usbr.gov/amp/index.html). The experiment began on January 1, 2003. Due to insufficient sediment input, there was no flood flow to store sediment. But high daily fluctuations ensued (5,000–20,000 cfs) and continued seven days a week for three months. To assess impacts, in April all of the Adopt-a-Beach study sites were re-photographed by volunteers. Late in the month the gcmrc sediment team ran a trip to monitor the results. I ran a trip and made the observations below.Some observations of sediment distribution,
April 9–25 river trip:
Following are recent general observations of the effects of the January-March high fluctuating flows to sand bars/camping beaches on the Colorado River and Lake Mead.

1) Sand bars are increasingly stripped of post-dam sand (identified by its lack of silt and clay). This has exposed increasingly extensive areas of the ‘hard pan’ of pre-dam silty sand and/or rocky shorelines that now armor the remains of many popular camping areas. Some examples of such camps include: Soap Creek, Hot Na Na Wash, North Canyon, Nautiloid Canyon, Buck Farm Canyon, Saddle Canyon, Nankoweap main and lower camps, Cardenas Creek, the “Cremation” camps, Trinity Creek, Monument Creek, Crystal Creek, Bass camp, across from Deer Creek, upper National Canyon, the Whitmore helicopter pad, 202-mile and Granite Park (measured by the difficulty of pounding in your sand stake).

2) The 20,000 cfs daily maximum flows reworked much of the higher elevation eddy sand into benches that are ten to fifty centimeters below the 20,000 cfs stage height. These same flows stripped additional amounts of fine sediment from the channel margins between the larger eddy systems. Shorelines and landings between eddy complexes are generally rockier. Some of the larger eddies contain large amounts of underwater sand (check out Carbon Canyon).
3) All reaches of the Grand Canyon from Lees Ferry to Separation Canyon are similarly affected. These patterns of erosion and redistribution of fine sediment are not restricted to the Marble Canyon reach.
4) Many of the newly formed 20,000 cfs sand bars are emergent and available for recreational use during the present daily maximums of 13,000 cfs. But, they are now being cut back by these flows, and will be inundated when daily maximums reach higher levels during the primary commercial season.
5) Due to low reservoir levels, the Colorado River is reclaiming the upper fifty miles of Lake Mead. Gneiss Canyon Rapid is beginning to show itself (RM 236). The current slows through “sand bar alley” (about river mile 254 to river mile 260) but the channel is still navigable (not advisable at night). The Lake Mead delta is being actively incised with fast current (about three to six knots) below Quartermaster Canyon (river mile 260). It flows through a shallow ‘canyon’ of deltaic sediments below the Grand Wash Cliffs (river mile 276). The current increases in velocity below Quartermaster, is increasingly channelized, and is very turbid between the Grand Wash Cliffs and middle of Iceberg Canyon where it abruptly terminates in the clear water of Lake Mead. The new rapid at the mouth of Pearce Bay is getting larger and more technical with the obstacles apparently composed of resistant deltaic mud towers (not advisable at night). The bay at South Cove is soon to be bathymetrically surveyed by gcmrc for its future viability as a takeout for river trips and launching of lake trips.
Summary:
In providing these observations, I do not intend to preempt or influence the outcome of ongoing sedimentologic work. I do look forward to seeing the results of current gcmrc sediment monitoring when it becomes available this summer. I am disappointed that gcmrc did not employ their bathymetric survey system (multibeam) for their April survey. It’s the best and only way to see what’s happening underwater.
I anticipate that the full impact of reduced camping beaches will be felt in June-August, when dam releases are highest and demand for carrying capacity is at its peak. The loss of low elevation sand may force greater use of the old high water zone for camping, with attendant impacts to these sensitive areas that are no longer renewed or buttressed by deposits from large floods.
The Experimental Flow program was designed to solve fundamental problems caused by rod dam operations. Until the river receives sufficient sediment to trigger a Beach Habitat Building Flow from the dam, we will be working in a highly depleted sand resource, especially for those of us without gills. Feel free to comment.

Andre Potochnik, Ph.D.
Adaptive Management Work Group