LEES FERRY – The Nationwide Park Service will poison a Colorado River facet channel beneath Glen Canyon Dam to take away fish that threaten native species, the company introduced.
In the meantime, biologists warn, rising temperatures and declining oxygen ranges in water the dam releases into the river’s Lees Ferry stretch are stressing the favored trout fishery there.
Nonnative smallmouth bass are identified to have handed by the dam’s hydropower-generating generators for a number of years to succeed in the Lees Ferry space, however their profitable breeding at that stretch was not documented till this yr. If it continues, bass may set up themselves far downstream and eat humpback chubs, that are protected as a threatened species.
“Threats to the native fish are rising because of the hotter temperatures of water passing by the dam and associated elevated river temperatures beneath the dam,” in keeping with a press release launched by Glen Canyon Nationwide Recreation Space, which incorporates the river phase.
Hotter water aided bass in spawning beneath the dam.
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Fish stocked within the river are actually a possible menace
Past bass and different launched sportfish that swim simply above the dam and will push by, brown trout that the Park Service itself stocked for anglers within the river in the course of the twentieth century are a possible menace. For that purpose, anglers now can declare a bounty for browns that they kill within the river.
However worsening river situations are actually threatening the rainbow trout fishery, which is taken into account much less harmful to native fish and helps a number of fly-fishing information companies.
The U.S. Bureau of Reclamation, which operates the dam, mentioned this month that the identical drought situations which have plunged Lake Powell’s water ranges into disaster are actually leaving Lees Ferry water oxygen-starved. Hotter water has much less dissolved oxygen, and the reservoir’s sinking floor elevation is inflicting flows by the dam’s tunnels to heat.
Like many points tied to the Colorado’s shrinking water provides, this one is accelerating.
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Low oxygen ranges can stress and kill trout or power them to maneuver downstream previous the place riffles add oxygen again into the flowing water. For now, trout stay evident in abundance at Lees Ferry.
Fishing stays good, although tailwater temperatures that must be round 50 levels in summer season are as a substitute roughly 70, mentioned Wendy Gunn, who owns and operates Lees Ferry Anglers.
“The meals base remains to be good,” Gunn mentioned, “so we’re nonetheless seeing wholesome fish, however we’re beginning to see fish battle and we’re seeing some lifeless fish.”
The reservoir’s continued decline may heat the river additional subsequent summer season, worsening the oxygen depletion.
What’s getting used to kill invasive fish, why do some native tribes object?
The company handled the slough with the fish killer rotenone on Saturday and Sunday. A second remedy could also be essential inside two months if extra invasive fish are discovered to have hatched or hidden within the space’s dense vegetation.
Whereas rotenone is a plant-derived chemical generally utilized by fish managers, and the Park Service mentioned it’s going to fastidiously shield the setting and human well being by isolating it within the slough, no less than one Native American tribe with cultural hyperlinks to the river and Grand Canyon has objected.
The Zuni Pueblo of New Mexico supplied The Arizona Republic a Sept. 8 letter that Zuni Gov. Val Panteah Sr. despatched to Glen Canyon’s appearing superintendent.
“The Zuni objection is grounded in our conventional cultural values and the enduring Zuni kinship relationship to all non-human life types (vegetation, animals, bugs; native and non-native) which have the correct to life, liberty, and procreation inside their pure environments,” Panteah wrote.
Will river entry change?
After discovering the younger bass, the Park Service put in a material barrier to maintain them from leaving the slough and coming into the river. The company mentioned it’s going to put a water-purifying chemical, potassium permanganate, there and within the river simply upstream of the slough to neutralize the rotenone.
The slough will likely be closed in the course of the remedy, however the river – fashionable with each anglers and kayakers – will stay open.
The stretch of river from the dam to Lees Ferry is a spotlight within the authorities’s efforts to guard humpback chubs, which solely final yr had been downlisted on the endangered species checklist.
Observe Brandon Loomis on Twitter @brandonloomis.
