Little mussels, ‘big deal’

By DENNIS WEBB

Dennis.Webb@gjsentinel.com

It would take a microscope to even see some young creatures that have caused an outsized stir among area water and wildlife officials with their discovery last month in the Colorado River and Government Highline Canal.

Those officials say the invisible-to-the-naked-eye juvenile zebra mussels, known as veligers, are nothing to be trifled with. When they become adults, though still only fingernail-sized, they reproduce quickly, impair pipes and other infrastruc-ture by attaching to them in huge numbers, and vacuum up plankton relied on as a food source by other aquatic species, resulting in both economic and ecological impacts that are best avoided to the degree possible.

“Some folks will ask, like, so what’s the big deal?,” Colorado Parks and Wildlife Director Jeff Davis told the agency’s commission at its July meeting. “Zebra mussels are plankton feeders. They can crash a fishery in a millisecond if you let the populations get too big, so there’s big ecosystem consequences if this gets out of control.”

He said they also can do some real harm to water infrastructure.

“We want to let the public know that we’re all over this one, and it’s not just us, it’s our partners,” Davis said.

Tina Bergonzini, general manager of the Grand Valley Waters Users Association, which operates infrastructure including the Government Highline Canal, said that based on comments she’s seen or heard in venues such as social media, she thinks people are failing to understand how detrimental mussels can be to the environment and to infrastructure.

She said some people think the mussels have been here forever, mistaking them for clams, and say they are good for the environment by cleaning the water as filter feeders.

“Yes, zebra mussels do clean the water. They clean it to the point (that) baby fry of native fish don’t have anything to eat and starve to death,” she said.

She is particularly concerned about keeping the mussels from damaging the Grand Valley’s vital and expensive water infrastructure that supports agriculture — including local orchards and vineyards — and the related agritourism industry. And that’s not to mention the potential impacts of mussels to entities like the Clifton Water District, which sources its water from the Colorado River.

“We sure don’t need zebra mussels plugging up their infrastructure and making it difficult for them to deliver water into people’s homes,” she said. “So the mitigation of the mussels is really top of the list right now of importance for all of the water entities in the Grand Valley.”

‘VERY SURPRISING’

The discovery of the larval-stage mussels came as a surprise to people including Bergonzini and Robert Walters, Parks and Wildlife’s invasive species program manager. Neither zebra nor quagga mussels, two invasive mussels species of particular concern, were known to be currently living in Colorado until adult zebra mussels were discovered at Highline Lake in 2022. Parks and Wildlife and partners have worked for years to do things such as inspections and decontamination of boats entering state waters to try to keep the mussels and other invasive species out of those waters.

Parks and Wildlife has been working to try to eradicate them at Highline Lake and the agency had begun doing regular testing in nearby waters to make sure the species wasn’t present elsewhere in the area.

See MUSSELS, page 10A ➤

Two PVC pipes show the type of damage that zebra mussels can do in masses, clogging important pipes, drainage ways, a vital issue for watering Colorado’s many crops, as well as the issue of mussels impacting food sources for local species. The pipes were shown by Bob Czarnik, lead aquatic nuisance species inspector for Colorado Parks and Wildlife at the Corn Lakes boat ramp on Friday.

Photos by LARRY ROBINSON/ The Daily Sentinel

Clifton Water District District Manager Ty Jones pulls up a zebra mussel trap out of the Colorado River on Thursday after the larval stage of the mussels were found in the river in July. No mussels have been located in the roughly two weeks that the makeshift trap was lowered in the water, with a secondary trap located at a different spot along the river in the Grand Valley for a different testing site. The mussels would simply latch on to the trap as they floated thorough the river, if present.

This 2023 map shows locations of quagga and zebra mussels occurrences in the United States, including a zebra mussels infestation at Highline Lake. Juvenile zebra mussels also now have been found in the Government Highline Canal and Colorado River.

U.S. GEOLOGICAL SURVEY

This photo shows a zebra mussel veliger discovered by Colorado Parks and Wildlife in the Colorado River near Grand Junction after routine testing in early July. A veliger is the mussel’s free-floating larval stage and can only be seen under a microscope.

COLORADO PARKS AND WILDLIFE PHOTO

. Continued from page 1A

For a while, no signs of the mussel showed up. But a plankton sample collected by Parks and Wildlife aquatic nuisance species personnel from the Government Highline Canal near Clifton on July 1 was found to have a suspected single veliger in it, and the sample later tested positive in a lab for zebra mussel DNA. Parks and Wildlife collected plankton samples on July 8 from two locations in the Colorado River upstream of the Grand Valley Water Users canal diversion. Single suspect zebra mussel veligers were found in both samples, which then tested positive for zebra mussel DNA.

The findings meant the canal and river were considered suspect for the presence of zebra mussels. But in a matter of days, an additional veliger was discovered and confirmed in the canal, and two more were found and confirmed in the Colorado River at two separate locations between De Beque and Grand Junction, meaning the canal and river are now considered positive for zebra mussels. The furthest upstream veligers have been found is the Beavertail Tunnel area in De Beque Canyon. No adult mussels have been found in the river or canal.

After the years of nondetections in samples taken in response to the Highline Lake situation, “it was very surprising to see these (veligers) show up in the canal and the river,” Walters said.

Parks and Wildlife is trying to determine what the source of the veligers may be. The veligers are not capable of moving themselves upstream, and the assumption is they flowed downriver from some upstream source, Walters said.

That western Colorado is dealing with a zebra mussel rather than quagga mussel problem also is somewhat surprising. Zebra mussels are mostly present in states east of Colorado. Quagga mussels are prevalent both in the East and in western waters such as Lake Powell, and it’s always been assumed that their presence in Powell posed one of the prime threats of a mussels infestation at a body of water such as Highline. Parks and Wildlife this year even began operating a season-long boat check station at the Loma Port of Entry on Interstate 70 largely with the goal of intercepting mussel-infested boats from Lake Powell.

Over the years, Colorado has had some cases of lakes or reservoirs, including ones in the Colorado River watershed, testing positive for zebra or quagga mussels, though adult mussels never were discovered. This happened at locations such as Granby Reservoir and Grand Lake in 2008, with the discoveries of one veliger at each water body. Blue Mesa Reservoir tested positive for quagga mussel DNA over a couple of years. Green Mountain Reservoir tested positive for quagga mussel veligers in 2017. No adult mussels were found in such instances, and after subsequent testing showed no further evidence of mussels, such water bodies are currently considered negative for the invasive mussels.

Walters thinks it’s likely in the local situation, with veligers being found in multiple sampling events on different dates, that the zebra mussels are established somewhere in the river system.

DECADES OF SPREAD

According to the U.S. Geological Survey, zebra mussels probably arrived in the Great Lakes from Europe in the 1980s in ballast water discharged by ships, and spread elsewhere in the country from there. A single zebra or quagga mussel is said to be able to produce up to a million offspring a year.

In terms of their ecosystem impact, a 2021 Bureau of Reclamation report cites prior research indicating that waters infested with mussels such as quagga and zebra mussels have been documented to experience reductions of up to 87% in planktonic biomass.

One concern locally with zebra mussels in the Colorado River is potential impacts on federally endangered and threatened fish locally. These include the razorback sucker, humpback chub, bonytail and Colorado pikeminnow.

“I think we’re so early on in the process I’m really hesitant to lay out a whole bunch of scenarios of what could possibly happen. I think the range is broad at the moment,” said Julie Stahli, director of the Upper Colorado River Endangered Fish Recovery Program.

She said she appreciates Parks and Wildlife’s efforts to find the source of the veligers, and her program is watching the situation carefully.

“We really need more information before we figure out what the appropriate steps are or really focus in on where our concern areas would be,” she said.

One concern for Bergonzini is protecting a multi-million-dollar fish screen her organization operates to help comply with Endangered Species Act protections for the imperiled fish. When fish are diverted at the roller dam in De Beque Canyon and into the canal system, the screen helps reroute those fish back into the river. Bergonzini worries about the potential for mussels accumulating on and plugging up things such as the piping that returns them to the river.

The Grand Valley Water Users Association and Orchard Mesa Irrigation District also want to protect a more than $10 million investment in the recently completed Vinelands hydroelectric power plant on the river, which replaced an aging plant.

“Obviously maintaining the integrity of that power plant is incredibly important,” Bergonzini said.

She said a mussels specialist already has been brought in from California to look at local infrastructure and identify weak points when it comes to vulnerability to mussels, and to suggest what kind of mitigation is possible. That could range from chemical and biological treatments to kill off mussels to applying coatings to infrastructure to keep mussels from being able to attach to them.

Bergonzini said local peach and grape growers have done a great job of improving water infrastructure to meet the climate crisis and make their operations more drought tolerant and sustainable. That means a lot of acreage is now under micro drip irrigation, and she fears that with the narrow gauge of piping that is involved in it, it wouldn’t take much for zebra mussels to plug up the delivery of water.

The Grand Valley Water Users Association also has more than 150 miles of laterals, and Bergonzini worries about the potential impacts of mussels on things such as the piping, valves and meters in that system.

MITIGATION MANDATORY

While other states have been dealing with quagga mussels and zebra mussels for a while, she noted that some of her association’s infrastructure dates back decades and in some cases even to the early 1900s and wasn’t designed for the invasive mussels.

“We have to mitigate for them,” she said of the mussels. “We can’t just live with them. Just living with them is going to come at a financial cost to the residents of the Grand Valley because everything is going to be more expensive — irrigation water, municipal water, goods and services. It’s going to be something that we’re going to have to address.”

“We’re all kind of in this together,” Ty Jones, manager of the Clifton Water District, said of local domestic and irrigation water providers. “... This is definitely a big deal.”

He said his district’s concern is the potential for mussels to block off the flow through intake infrastructure before the water reaches its treatment facilities. The district is now using mechanisms to monitor for the possible presence of mussels.

He’s trying to remain optimistic due the fact that adult mussels haven’t been found in the river, but adds that if adults start showing up, there are going to be expenses for water providers and consumers.

He said Clifton Water is looking to learn from others that deal with mussels now. He said there are some chemical treatments for mussels that are approved for use in drinking water. Whatever Clifton Water might use would have to meet standards for safely drinking the water. The district also needs to ensure that whatever it might do is workable for its membrane-based treatment process.

As one indication of the costs invasive mussels can create, the 2021 Bureau of Reclamation report said researchers surveyed 13 dams in the United States and Canada, among them Hoover Dam and Glen Canyon Dam, and found that nine of them each spend about $464,000 a year on increased maintenance related to mussels. Four others don’t have annual maintenance but have reoccurring, intermittent maintenance costing about $650,000 per occurrence.

“Of major significance to facilities is the ability of mussels to rapidly colonize hard surfaces at densities of tens of thousands of mussels per square meter, as well as generate a significant volume of shell debris that may be transported from upstream colonies,” the report said.

It said the mussels can impact things such as conduits, canals, intake orifices, gates, drains and pumps, with flow restriction typically being the foremost concern. Mussel fouling also can contribute to corrosion of metal infrastructure.

Local Bureau of Reclamation spokeswoman Justyn Liff said the mussels discoveries in the area are disappointing, and she thinks they will affect water users and the endangered fish program.

“I think right now where we’re at is we’re still definitely in the gathering information stage, looking at additional testing, working with our partners at Colorado Parks and Wildlife,” she said.

She said Reclamation’s Technical Service Center in Denver has gotten involved in providing information about things such as options for sampling and eradication, and what might work in the Colorado River.

IDAHO’S RIVER RESPONSE

Last fall in Idaho, state personnel applied a copper-based chemical treatment to try to eradicate quagga mussels in a six-mile stretch of the Snake River after the mussels were found near Twin Falls in September. Colorado Parks and Wildlife similarly has used a copper-based treatment to try to kill off mussels at Highline Lake. Walters is watching with interest Idaho’s attempts to do so in a river rather than a more contained body of water.

The state of Idaho says early indications are the treatment worked, but monitoring will go on for five years to ensure the mussels have been eliminated. Walters said he isn’t surprised the treatment killed mussels, which it is intended to do, and there is some promise there, but it will take several years to determine the approach’s success in killing off the species in the river.

As efforts to better assess the local mussels problem and consider responses to it continue, entities such as the Bureau of Reclamation and Parks and Wildlife are in the meantime emphasizing the need to employ some invasive species hygiene on local waters. There’s been a particular emphasis on that by Parks and Wildlife on the Colorado River with the knowledge that mussels are now present there. Agency staff have been spending time at local boat ramps emphasizing the need for people to clean, drain and dry their watercraft and equipment, to help prevent further spread of the mussels.

Parks and Wildlife spokeswoman Rachael Gonzales said that with zebra mussels’ potential for devastating impacts, as long as the mussels are here, “we want to prevent the spread of those devastating impacts to other areas around the state.”

This photo of mussels-encrusted water infrastructure at Glen Canyon Dam was used to illustrate a 2021 U.S. Bureau of Reclamation report on the costs associated with impacts of invasive zebra and quagga mussels on infrastructure such as at hydroelectric plants.

PHOTO BY C. SHANE MOWER/ U.S. Bureau of Reclamation

Bob Czarnik, Lead Aquatic Nuisance Species Inspector with Colorado Parks and Wildlife, left, speaks to a member of the public about the ongoing Zebra mussel issue and how boaters and rafters should go about checking and cleaning their belongings after each use in a body of water or river way, including forgettable things like coolers for drinks. Half of Czarnik’s job when it comes to mussels is informing the public how to help the issue before it gets too hard to manage, he says.

LARRY ROBINSON/ The Daily Sentinel