Grand Valley water managers have a plan to nip a potential zebra mussel infestation in the bud, with one irrigation district beginning treatment of its water this fall.
Officials are hoping to secure federal funding to treat the water that irrigators and domestic water providers pull from the Colorado River with liquid ionic copper, which kills zebra mussels. Mesa County plans to ask for the money through the U.S. Bureau of Reclamation’s Bucket 2 Environmental Drought Mitigation program.
Microscopic zebra mussel larvae, known as veligers, were found this summer in the Government Highline Canal, a crucial piece of irrigation infrastructure for the Grand Valley’s agricultural producers. If these aquatic invasive species become established, it could be disastrous for the region’s farms, vineyards, orchards and Colorado’s famous Palisade peaches. The fast-reproducing mussels, which are native to Eastern Europe, can clog water infrastructure and are incredibly hard to eradicate once established.
“Our concern is for our smaller partners,” said Tina Bergonzini, general manager of Grand Valley Water Users Association. “Many of our commercial peach growers and vineyards use microdrip irrigation. It would take just absolutely nothing to pinch off those systems completely, and it would be catastrophic. … It could absolutely cripple agriculture from Palisade clear to Mack depending on the extent of the infestation.”
Mesa County plans to apply on behalf of the irrigation districts and water providers for more than $4 million in funding, which will come from the remaining $450 million of Inflation Reduction Act funding for projects in the Colorado River’s Upper Basin (Colorado, New Mexico, Utah and Wyoming). “B2E” funding, as it’s called, is intended for projects that provide environmental benefits or ecosystem restoration and must be awarded to public entities or tribes. Several irrigation districts and domestic water providers would take part in the copper treatments: GVWUA, Grand Valley Irrigation Company, Orchard Mesa Irrigation District, Palisade Irrigation District, Mesa County Irrigation District and Clifton Water.
“Mesa County recognizes the serious threat posed by the recent discovery of zebra mussels in the Colorado River and the Government Highline Canal,” Mesa County Commissioner Bobbie Daniel said in a written statement. “We understand the urgency of the zebra mussel situation, and that is why Mesa County is leading the charge in applying for federal funding to tackle this issue.”
Palisade Irrigation District is not waiting for federal funding. It plans this fall to begin treating with copper the roughly 8 miles of the Price Ditch and its many laterals that irrigate about 5,000 acres of orchards, vineyards, alfalfa, cornfields and lawns. PID gets its water from the Government Highline Canal.
PID Superintendent Dan Crabtree saw the issues with quagga mussels, a relative of zebra mussels that causes similar problems, in Lake Powell on his yearly trips to the reservoir and knew mussels could someday become a problem for the Upper Basin too.
“It just seemed inevitable that we would get them up here somehow,” Crabtree said. “The Palisade Irrigation District actually started a line item in our budget for this very thing maybe four years ago, so we’ve got a little money set aside. Our system, I believe, is very susceptible to mussels because we are all pipes.”
Crabtree said PID plans to start the copper treatment in October, which will cost the district about $60,000.
Copper has been used by water providers in the Colorado River’s Lower Basin (Arizona, California and Nevada), including the Central Arizona Project, to kill invasive mussels that threaten infrastructure. Experts say the treatment doesn’t harm fish or crops.
“What we are leveraging here is the fact that zebra mussels happen to be very, very sensitive to copper, even in the low parts per billion range,” said David Hammond, a senior scientist with Earth Science Labs, which manufactures the liquid ionic copper under the brand name EarthTec QZ. “I certainly understand people are cautious about pesticides and they want to make sure it’s been vetted and that it’s prudent use, and I share that perspective. This is very safe for people and for food.”
GVWUA flew Hammond in from California to look at their infrastructure and advise them on a plan of action.
“It looked scarily susceptible,” he said. “Almost everywhere you look, there seemed to be places of concern.”
Focus on prevention
In August, staff from Colorado Parks and Wildlife gave an update on zebra mussels at a meeting of the state legislature’s Water Resources and Agriculture Review Committee. Robert Walters, manager for CPW’s Invasive Species Program, told lawmakers that nonnative mussels are the most-costly invasive species in the United States and the highest priority for the state’s invasive species program.
“Once they are established, eradication is nearly impossible,” Walters said. “What we really, really focus on is prevention. It is really, really difficult to remove these, so we want to do everything we can to keep them out in the first place.”
Walters said there are three characteristics that make zebra mussels extremely detrimental: They reproduce prolifically, with a single female able to produce 1 million juveniles in a year; they attach to hard surfaces with something called a byssal thread, which acts like an anchor and makes them hard to remove; and they can each filter up to 1 liter of water a day, stripping the plankton and nutrients that form the base of the food web, which could lead to the collapse of fisheries.
Mussel veligers have been detected in several Colorado lakes since 2008, but adult mussels had not been found until 2022 in Highline Lake, on the northwest end of the Grand Valley. Highline Lake was treated with liquid ionic copper in March 2023.
In July, testing found the mussel veligers in the Colorado River in two other locations: the Blue Heron boat ramp in Grand Junction and the Beavertail Mountain Tunnel pull-off, just upstream from the Cameo diversion in DeBeque Canyon. The source of the mussels remains unclear, but officials suspect it may be a small upstream lake or pond.
“Our focus now is really on the monitoring,” Walters said. “We really, really want to know where these are coming from and how far the extent of that population is.”
In addition to continued water sampling, CPW staff is doing everything it can to educate the public on the severity of the issue and what people can do to help stop the spread into other bodies of water, such as cleaning and drying their equipment. Walters said officials have contacted 164 outfitters that use that stretch of river and have spoken with more than 3,000 people recreating on the river. CPW and its partners also have 77 boat-inspection locations around the state and perform more than 500,000 watercraft inspections annually, Walters said.
Thirty-five boats with mussels on them have been intercepted at the Loma port of entry so far this year. Decontamination involves blasting a boat with 140-degree water for 10 seconds, which kills the mussels, and then a high-pressure wash to remove them from the boat.
Applications for the federal B2E funding are due by Oct. 14. Even if the Grand Valley water users are awarded the money, Bergonzini said they probably won’t get it until about a year from now, meaning they will have to be hypervigilant about mussels through another irrigation season.
“We are also just trying to make sure that we’re continuing testing our canals to see if we find more,” she said. “It’s like a really frustrating game of hide-and-seek. You don’t want positive results, but then when you don’t get positive results, then it’s so frustrating because it’s like, ‘Where are you?’”