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Wildlife experts still hunting for source of invasive mussels in Colorado River

This tiny young zebra mussel larvae was found in water from the Colorado River near Grand Junction. Wildlife officials are doing more tests to find the source of the invasive mussels and stop them from establishing.
Courtesy of Colorado Parks and Wildlife
This tiny young zebra mussel larvae was found in water from the Colorado River near Grand Junction. Wildlife officials are doing more tests to find the source of the invasive mussels and stop them from establishing.

Water users in Western Colorado are awaiting results of ramped-up testing efforts to control invasive zebra mussels after they were found in the Colorado River and an irrigation canal near Grand Junction. The mussels spread quickly, and can cause wide-reaching harms such as damage to irrigation equipment and disruptions to river ecosystems for native fish.

Ongoing testing is aimed at finding the source of the young zebra mussel larvae and stopping them before they become fully established.

“It's really kind of looking for a needle in a haystack,” said Rachel Gonzales, a spokeswoman for Colorado Parks and Wildlife.

Colorado Parks and Wildlife found young zebra mussel larvae during routine testing in early July. A few weeks later, more samples from two different locations in the Colorado River included those young mussels, called veligers. Another sample, taken from the Government Highline Canal also had a mussel veliger.

This undated file photo provided by the U.S. Department of Agriculture shows a group of zebra mussels. The invasive species
AP
/
U.S. Department of Agriculture
This undated file photo provided by the U.S. Department of Agriculture shows a group of zebra mussels. The invasive species

State officials and local agricultural leaders have sounded an alarm about the mussels, which had never before been seen in that particular stretch of the Colorado River. Tina Bergonzini, Grand Valley Water Users Association General Manager, called the discovery “devastating.”

The mussels, which latch on to hard surfaces, can clog irrigation pipes and cut off farmers from their water supplies. That would cause harm for the area’s economy, much of which relies on irrigation.

“The Grand Valley is based on agriculture,” Bergonzini said. “A lot of it is vineyards and peach growers. So having zebra mussels get infested into the infrastructure of our commercial ag growers hits not only the agricultural industry, but also our tourism industry.”

Bergonzini’s agency, which provides irrigation water to more than 23,000 acres in Mesa County, is working with an environmental consultant to come up with a response plan. She said the consultant has learned from other mussel infestations in the region. Similar mussels are a persistent challenge for some water providers in the lower portion of the Colorado River Basin, such as the Central Arizona Project, which carries Colorado River water to the Phoenix area.

Cattle graze in the Grand Valley on Jan. 25, 2024. Farm groups say the area's growers will benefit from the Colorado River District's acquisition of the Shoshone water right because it will help them have more predictability in the amount of water they can divert for farms and ranches each year.
Alex Hager
/
KUNC
Cattle graze in the Grand Valley on Jan. 25, 2024. Farm groups say the area's growers will benefit from the Colorado River District's acquisition of the Shoshone water right because it will help them have more predictability in the amount of water they can divert for farms and ranches each year.

“We are going to be quite aggressive with mitigating and managing moving forward to make sure that we don't have the presence of adult mussels,” Bergonzini said.

Wildlife experts also worry about the impact of zebra mussels on the river food chain. They eat small aquatic prey like plankton, adding new competition for fish with similar diets.

Zebra mussels and a related species called the quagga mussel are widespread throughout the Great Lakes region and other areas east of the Colorado River basin. Native to Europe, they were likely introduced and spread throughout parts of the U.S. by boats. To stem further spread in the Southwest, wildlife agencies track boats to prevent cross-contamination and require boaters to clean, drain and dry their watercraft before putting them back in a new body of water.

This story is part of ongoing coverage of the Colorado River, produced by KUNC in Colorado and supported by the Walton Family Foundation. KUNC is solely responsible for its editorial coverage.

Copyright 2024 KUNC

Alex is KUNC's reporter covering the Colorado River Basin. He spent two years at Aspen Public Radio, mainly reporting on the resort economy, the environment and the COVID-19 pandemic. Before that, he covered the world’s largest sockeye salmon fishery for KDLG in Dillingham, Alaska.