GCPBA RiverNews 2/26/17 – Glen Canyon Dam HFE/Adaptive Management Report

GCPBA RiverNews 2/26/17 - Glen Canyon Dam HFE/Adaptive Management Report

Grand Canyon Private Boaters Association board member John Vrymoed was on a Grand Canyon river trip during the November, 2016, high flow. His experience during it led him to contact the people who manage Glen Canyon Dam to give them his comments and input of how it could be improved for private boaters. He attended their Adaptive Management meeting in January.

His report is below. We thank John for taking time to attend the meeting on behalf of GCPBA and private boaters.

How I Ended Up in a Meeting with a Group of Grand Canyon Scientists
by John Vrymoed

While I was camping at Matkat Hotel, 149 miles from Lees Ferry in Grand Canyon, I went down to the river’s edge in the early morning hours to see how our boats fared at the end of the ramp-down period of the November, 2016, High Flow Experiment (HFE). (The river flow went from about 9,000 cfs to 36,000 cfs, then back down to 10,000 during one week's time). It was not a pretty sight. One boat was completely out of the water on a flat portion of beach. My Big Daddy Cat was precariously cantilevered on a massive boulder, four feet above the water line. Others fared a little better, having come to rest on a steeply sloped portion of beach and were easily pushed back in the water. Needless to say, it was slow getting going that morning.

The high flow, having started on Nov 7, 2016, reached us while we were camped at Lower Bass. We sat out that first day of the HFE and hiked. Never having experienced a flow of 36K, we were all a little apprehensive that following morning. What’s Specter Rapid going to be like, or Bedrock, or Deubendorff? Much to our relief, all the rapids were made easier. Not so for the group behind us, who had two boats flip in Crystal.

While unloading/reloading the boats at Matkat, I became aware that the ramp-down rate was too fast, as it didn’t allow for the newly deposited sand to adequately drain. As a result, the slope was caving, losing what sand had just been deposited. This phenomenon was noticed as we went down that day; the steeper slopes had rivulets as water flowed back to the water line, with portions of the slope caving.

If the high flow releases are an experiment, why not lower the ramp-down rate and perhaps increase the already beneficial aspects of the HFE's? Being a retired geotechnical engineer, I felt strongly enough about this to author a letter for the Grand Canyon Private Boaters Association to send to the US Bureau of Reclamation, suggesting that a slower ramp-down rate be considered for future HFE's.

The overall impact on beaches was positive, especially those having a gentle slope.  Some of the steeply sloped beaches suffered damage due to calving, as seepage had not had enough time to adjust to the receding water level during the ramp down portion of the experiment.  As a result, the material that was deposited was lost.

This trip piqued my interest in HFE's, as well as making me curious of the purpose and results of all the “science” trips many of us have encountered while going down the river. To satisfy my curiosity, on behalf of the GCPBA I decided to attend the Glen Canyon Dam Adaptive Management Annual Meeting held on January 24, 2017, in Phoenix. I’m glad I did. I’m a long time boater and am conversant with the NPS requirements for noncommercial boaters, negotiating the rapids, the number of groover cans needed per person for X number of days of a river trip, etc. This was a chance to learn about all the other aspects that I’ve always ignored and had not cared about.

HFE's: Whether or not one is done is dependent on the available sand to be moved as a result of sand deposited by flows in the Paria River and Little Colorado River. An HFE results in a monetary loss due to no electricity being generated at Glen Canyon Dam because HFE water has to be released through the bypass tubes. How much of a loss depends upon the number of generators online at that time.

Also, I didn’t know that there are about 10 cameras installed throughout the Grand Canyon river corridor to monitor beach erosion. I had heard references of cameras and assumed they were monitoring us boaters.

A good synopsis of beach building was provided during the poster session. This information was put together by Katie Chapman, who is a student at Northern Arizona University. This work was done under the auspices of the United States Geological Survey. Beach Building Poster

Humpback Chub: Is the size of the population of this native fish affected by water temperature, available food supply, or predation? Predation by trout or by mature humpbacks? Or, are they not being caught, which is easier in the Little Colorado River than the Colorado River. A lively discussion ensued regarding which factor most influenced the health of this odd looking fish.

Vegetation: Well, we all know that there is more vegetation now than there used to be. What was interesting were the comparison photographs taken during the Stanton survey in 1889 with those recently taken in the same exact locations. If interested, type “Stanton repeat photography” in your browser. As an example, it is interesting to see what Parashant looked like in 1889.

Stanton Repeat Photography

A survey of 832 private boater's experience in Grand Canyon indicated the following:

* On their trips, 75% experienced a flow 13,000 cubic feet per second
* The most preferred flow was 22,000 cfs
* The least preferred was 5,000 cfs

The preferred flows where found to have a net economic value. When asked, the folks surveyed were willing to roughly pay $700 above trip costs to have a flow of 22K as opposed to 5k. Interesting.

A good aggregation of info regarding HFE's, fish, etc., and the science behind, it is available at: Glen Canyon Dam Adaptive Management. This page is the Wikipedia version of all the science related topics. Check it out.

Well, something good did come out of having to unload my cat, lift it off the boulder, and reload it. I’m now more educated about one of my favorite places. Conversing with the scientists doing the studies, I was able to convey that this private boater cares and appreciates their work.

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