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New research identifies abundant endangered fish below waterfall in San Juan River

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Waterbaby

Escalante-Class Member
https://phys.org/news/2018-09-abundant-endangered-fish-waterfall-san.html

New research identifies abundant endangered fish below waterfall in San Juan River
September 19, 2018 by Mark Mckinstry, Bureau of Reclamation

Since the late 1980's, this waterfall formed from interactions among reservoir levels and sedimentation that redirected the San Juan River over a 20-foot high sandstone ledge. Until recently, little was known about its effect on two endangered fishes. Between 2015-2017, more than 1,000 razorback sucker and dozens of Colorado pikeminnow were detected downstream of the waterfall. Credit: Bureau of Reclamation

Read more at: https://phys.org/news/2018-09-abundant-endangered-fish-waterfall-san.html#jCp

Prolonged drought and increased water use in the southwest United States have led to shrinking reservoirs and the emergence of natural features that are affecting endangered species and river recreation. One feature, a waterfall known as the Piute Farms Waterfall, has formed in an area upstream of Lake Powell where the San Juan River serves as a border between the Navajo Nation to the south and Glen Canyon National Recreation Area to the north. Since the late 1980's, this waterfall formed from interactions among reservoir levels and sedimentation that redirected the San Juan River over a 20-foot high sandstone ledge. Until recently, little was known about its effect on two endangered fishes.

A new study published in the journal River Research and Applications provides insight into the magnitude of the effect this waterfall has on endangered fishes.

"Even though we knew the waterfall existed for decades, nobody knew how it affected the Colorado pikeminnow and razorback sucker, two endangered species that are the focus of a large interdisciplinary recovery program," explained Dr. Mark McKinstry, a research biologist from the Bureau of Reclamation and one of the coauthors of the study.

Since the inception of recovery programs in the Colorado River Basin in the early 1990's, endangered fishes have been tagged with "microchip" radio transmitters like those used to keep track of dogs, cats, and livestock. More recently, tag detection technology has allowed the construction of antennas that are small, portable, and submersible, thus allowing them to be used in places that were not feasible just a few years ago.

Researchers at the waterfall relied on a single, three-foot diameter antenna that looks like a plastic wagon wheel. This antenna, while only deployed seasonally from 2015-2017, detected over 1,000 razorback sucker and dozens of Colorado pikeminnow downstream of the waterfall. Some fish moved to this location from up to 600 miles away in the Colorado River. Additionally, mature razorback sucker physically captured downstream of the waterfall were expressing gametes, suggesting that spawning migrations may be cut off by the waterfall. The number of razorback sucker isolated downstream of the waterfall is proportionally large relative to the population upstream in the San Juan River, but biologists do not fully understand the ability of razorback sucker to spawn and grow in river-reservoir inflows. Connectivity among the Upper Colorado River, Lake Powell, and the San Juan River could be important for recovering endangered fish.


Reclamation Researcher Mark McKinstry holding a razorback sucker below Piute Farms Waterfall while conducting research. Credit: Bureau of Reclamation
Given recent water consumption and climate patterns, reservoir levels may be less than what is required to provide unimpeded fish passage in the long-term. This phenomenon is not isolated to the San Juan River. In fact, another emergent rapid and potential barrier in the Colorado River downstream of the Grand Canyon is so dangerous that the National Park Service constructed a multi-million-dollar road so river rafters could avoid the rapid by taking their rafts out upstream. This rapid may also impact endangered fishes that move between Lake Mead and the Grand Canyon.


"We know connectivity is important to fishes but these emergent river-reservoir processes could be further stressing populations," commented Casey Pennock, coauthor and graduate student at Kansas State University, "and its challenging researchers to better understand the resiliency of populations in systems that may never return to their historical conditions."

More research at the waterfall will help to manage the two fish species by providing information for future fishpassage and may shed some light on managing these unique features that could become more common in western rivers.

Explore further: Fish once thought extinct in Grand Canyon found in Colorado River

More information: Charles N. Cathcart et al, Waterfall formation at a desert river-reservoir delta isolates endangered fishes, River Research and Applications (2018). DOI: 10.1002/rra.3341

Provided by: Bureau of Reclamation



Read more at: https://phys.org/news/2018-09-abundant-endangered-fish-waterfall-san.html#jCp
 

Pegasus

Well-Known Member
If I read this correctly, the researcher is saying that because of the lower water level of Lake Powell and Lake Mead, a waterfall and a rapid are causing several endangered/threatened fish species to possibly be even more threatened/endangered because of the lack of connectivity between the river and lake(s).

Shouldn't they be arguing for less water to be released from Glen Canyon to help save the endangered fish near the Piute Farms waterfall? And for users of Lake Mead water to be cutoff to allow Lake Mead to rise to save these fish species?

Kidding of course, but I've definitely heard the argument the other way over the years - i.e. we need to drain Lake Powell to save endangered fish species. Yes, I'm suggesting there is some hypocrisy floating around......
 

Dorado

Escalante-Class Member
Except....the waterfall was created by the fluctuations in Lake Powell....

I wonder how hard it would be to force the river back into its original channel, where there is no waterfall?
 

John P Funk

Escalante-Class Member
Except....the waterfall was created by the fluctuations in Lake Powell....

I wonder how hard it would be to force the river back into its original channel, where there is no waterfall?
Don't give them any ideas, sounds like a "shovel ready" government job to me.
 

Waterbaby

Escalante-Class Member
Isn’t there a real 20 foot waterfall just upstream of this?
Isn’t there a real 20 foot waterfall just upstream of this?


Wayne can correct this if wrong, but this is a natural waterfall, with high water we boat right over it - you can see the depth finder change very rapidly. It's been years since we were able to boat all the way to and beyond Piute Farms, used to love to go up there because it was usually desolate except for fishermen who drove in and launched from shore in the area.
 

Gem Morris

Escalante-Class Member
I got the impression from my admittedly cursory reading of the article that this was some new waterfall created downstream from the historical one due to sediment buildup. Hence my question - why are they freaked out above a new waterfall below the historical waterfall - seems like 2 barriers are a lot like 1 barrier - a barrier to fish is a barrier to fish. I should prob read the article again
 
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Bill Sampson

Escalante-Class Member
Waterbaby, one time we went above Piute Farms, and you are right. Everything takes a total different look. We actually passed up some Indians on our way, and got a strange look from them. My buddy who was driving the boat always said he wanted to take the boat all the way up to Mexican Hat and have a margarita. We never made it that far, an I am not sure you can get a margarita in Mexican Hat.
 

Waterbaby

Escalante-Class Member
Waterbaby, one time we went above Piute Farms, and you are right. Everything takes a total different look. We actually passed up some Indians on our way, and got a strange look from them. My buddy who was driving the boat always said he wanted to take the boat all the way up to Mexican Hat and have a margarita. We never made it that far, an I am not sure you can get a margarita in Mexican Hat.

In the late 70's, early 80's we rented one of the 42' houseboats with another couple and we were able to go up the San Juan past the Clay Hills area. What an amazing week - we went in and out of every canyon on the San Juan. I think how young and dumb we were, if the houseboat had mechanical issues who knows how long before anyone located us - it was totally desolate up there, and oh so quiet! George remembered when he was young his uncle, who lived in Durango, used to go down the old road [the one Pete used to write about] with an old boat and go fishing up the San Juan. We had a huge sandy beach all to ourselves in the Piute Farms area - George and a friend wrestled a huge piece of driftwood to bring back, then we found out it was full of bugs [after all the work]... lesson learned. We started going up the San Juan every trip in the 90's and when the water was high could go quite a distance, I remember when we were in the Piute area running in the middle of the channel and George commented the depth finder had made a dramatic change to much shallower water [this is where we went over the waterfall - that we didn't know was a waterfall. I have always said I hope they never build another marina up there, having one part of the lake still relatively desolate is a blessing.
 
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Waterbaby

Escalante-Class Member
Except....the waterfall was created by the fluctuations in Lake Powell....

I wonder how hard it would be to force the river back into its original channel, where there is no waterfall?

Pretty much impossible, it is a big silt bed up there now. I know the last time we were able to get near, we didn't see the falls, it was the late 90's and I think they were still slightly underwater, but the bay beyond was beautiful and dead calm [I have pics somewhere - maybe on video], but it wasn't something you wanted to even try to boat into - maybe a kayak, but not a motor boat. here is a good article explaining the silt up there.... BTW if the water is dropping even below the Piute area the silt is deep and nasty - we let the dogs out and even they sunk into the black, stinky, stuff and then we had to get them and try and wash them off and back in the boat - that was the last time we went up there, it was before the drought so would have been late 90's or 2000ish. I know the last time went up any real distance we stayed in Mike's Canyon - that was in 2002 and the water was starting to get really grungy. The article below says the San Juan carried the heaviest sediment load of any river [I can't imagine more than the Mississippi ??]

I am curious how far Wayne goes up the San Juan these days for his fish sampling.

http://www.riversimulator.org/Resources/Contractors/SanJuanSiltStory1994.pdf
 

wayne gustaveson

Moderator
Staff member
I am curious how far Wayne goes up the San Juan these days for his fish sampling.

http://www.riversimulator.org/Resources/Contractors/SanJuanSiltStory1994.pdf

We sample in the Piute/Neskahi Canyon area with gill nets, electrofishing and trawling. We then go up as far as Alcove Canyon for an afternoon of sport fishing. If the lake is higher we go further but not this year. We have one more trip scheduled during the 3rd week of October. We had to move it up to beat the HFE scheduled for Nov 5th.
 

Squirrel

Escalante-Class Member
We Trash Tracked up to Alcove this past July. We don't have a Fish Finder on the runabout or Eliminator so I don't know what the depth was. Water
clarity was nil. Maybe 2 inches. Traffic was nil. Fireworks were nil. Wakeboard boats behind houseboat were nil.
Sounds like a great trip. Sq
 

Waterbaby

Escalante-Class Member
Sounds like a great trip. Sq
Unnerving when you are that isolated and have no water clarity - we tried it up the Escalante years ago - it was peaceful and calm but finally we chickened out and turned around, the water was like brown soup and the shore had tons of river rocks, I have wide angle picture [fading fast sadly] we took right before turning around........ I remember we were trying to get up to the waterfall. It's been years and years since you could get very far up either river [San Juan or Escalante]. People who are relatively new to the lake have a real treat in store someday when the rains come and the lake rises again.
 

Bill Sampson

Escalante-Class Member
A few years back we went a far as Zahn Bay, and the water was basically gray, and there were tree branches sticking out. We went no further than that. Cell phones don't work up there, so you are very remote.
 
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