The National Park Service announced plans to poison a section of the Colorado River to eliminate an invasive species of smallmouth bass.
“These non-native predatory fish were recently discovered breeding in areas where they have not previously been found in large numbers, threatening the recovery of humpback chub, which is listed as threatened under the Endangered Species Act (ESA),” the National Park Service said.
The project started over the weekend when the EPA-approved fish piscicide rotenone was released into the Colorado River below the Glen Canyon Dam in the Glen Canyon National Recreation Area.
Officials said they took precautions to ensure the poison does not harm humans, other fish species, livestock, and the local environment. To prevent the poison from spreading beyond the treatment area, an impermeable fabric barrier was installed at the mouth of the slough.
In addition, officials said that potassium permanganate, which purifies drinking water, will be dispersed into the water just above the fabric to neutralize any rotenone that escapes.
According to the Arizona Republic, officials first noticed the smallmouth bass on July 1 and installed a temporary barrier to keep them from leaving the slough, which is about three miles below the Glen Canyon Dam.
Officials said they will continue to monitor the situation and said that an additional treatment may be required in two months.