The Grand Canyon National Park web site has posted an information page on the possible High-Flow experiment set to release 41,000 cubic feet per second for the Colorado River through the park to begin March 5 lasting through March 9, 2008.
The high flow will occur by releasing water from Glen Canyon Dam, 14 miles upstream of the park boundary.
A final decision has yet to be made by the Department of Interior, and is expected within the week.
After the decision is finalized, Grand Canyon National Park will be notifying all permittees conducting a river trip to be alert for the High-Flow event. The Park has posted some information on river flows, campsite changes, and other river running related information at:
http://www.nps.gov/grca/naturescience/high_flow2008-permit.htm
Useful information is also found in a link to the Grand Canyon Monitoring and Research Center web site with estimated water levels at 46 selected campsites along the river. Individual maps show projected water levels in popular river runner camps such as South Canyon at 31.9 Mile, Carbon at 65.1 Mile, Cremation at 88.7 Mile, Pancho's, Football and Backeddy at 137.7, and the Upper and Middle 220 Mile camps, at 220 Mile. For more information see:
http://www.gcmrc.gov/research/high_flow/2008/maps.aspx
The Grand Canyon Monitoring and Research Center web site also has a table showing how the flow of water will move through the canyon at:
http://www.gcmrc.gov/research/high_flow/2008/files/2008_hfe_flow_schedule.pdf
It is estimated that over 20 self guided river trips will be traveling through some part of the canyon during the flood. Competition for campsites is expected to increase as the higher water levels inundate large amounts of traditional camps.
River runners can expect river flows of 6 to 8 miles per hour during the flood. This flow will decrease on-the-river travel times allowing more time in camp or for side canyon hiking. Higher flows "wash out" some rapids, making them easier, but the quicker current can make some more challenging. RRFW urges river travelers to scout all major rapids.
As part of the 2006 Colorado River Management Plan, Grand Canyon National Park had set aside March as a motor-free period for recreational river runners. However, during the release, river travelers can expect to see an unusually high number of motorized watercraft conducting scientific research before, during and after the high flow.
The experiment was conducted last in 1996 and 2004. Those tests revealed there is not enough sediment entering the river ecosystem below Glen Canyon Dam to make up for even a small percentage of the 44 million tons of sediment that would otherwise be entering the system on an annual basis were the dam not in place.
The High-Flow release scheduled for this March is only one-third the volume of the pre-Glen Canyon Dam flow that normally occurred in late May or June following a winter like the one at present, with a snowpack at 160% of normal.
RRFW would like to remind river runners heading to take out at South Cove that the new Pearce Ferry rapid at mile 280 is continually evolving. Now estimated to be a class 4 rapid (on a scale of 1-6), the higher flows may hasten changes at this rapid. The potential for accident or injury to an unwary trip at Pearce Ferry Rapid is high, particularly when night-floating.
River Runners For Wilderness
Promoting river resource protection through wilderness management