The presence of zebra-mussel veligers in the Upper Colorado River near Grand Junction has water managers concerned but not panicked.
“It’s a new discovery that’s a bit alarming,” the general manager of the Dolores Water Conservancy District, Ken Curtis, told KSJD.
Veligers are the microscopic larval stage of the mussels. Zebra and quagga mussels are invasive species that originated in Eastern Europe. They were first discovered in North American waters in 1988 in the Great Lakes.
They attach themselves to hard surfaces and can survive out of water for weeks, so they can be spread by boats, other watercraft, and gear such as anchors.
In mid-July, Colorado Parks and Wildlife officials announced that veligers had been found in two locations in the Colorado River upstream of the Grand Valley Water Users Canal Diversion, and in the Government Highline Canal near Clifton. After more sampling, CPW announced in late July that another veliger was found in the Government Highline Canal and two more veligers were found in the Colorado River between De Beque and Grand Junction.
In 2022, adult zebra mussels were found at Highline Lake near Loma, the first time invasive mussels were found in Colorado waters.
Although those sites are not connected directly to the Dolores River, Curtis says it is worrisome that the mussels’ range has grown.
“It expands their range in Colorado and that adds to the risk to other waterways,” he said.
Until the recent discoveries, the location nearest to Montezuma County where mussels had been found was Lake Powell.
“Now we’ve got another population about four hours away,” Curtis said. He noted that so far, however, no adult mussels have been found on the Upper Colorado, only the veligers.
The rapidly spreading mussels have enormous impacts on both ecosystems and infrastructure.
They are filter feeders that clean particles from water, but that can facilitate the growth of weeds because more sunlight penetrates the water. The invasive mussels also consume the microscopic plants and animals on which native species depend, out-competing them.
That alters which types of fish flourish. “Both native fish and trout, or any fish in the lakes, can be affected,” Curtis said. “They can potentially harm the whole food chain.”
Mussels also have what he called an aesthetic impact, as their rotting bodies on shorelines smell bad. And their sharp shells make it unpleasant and hazardous to walk on beaches. “There are all these ripple effects.”
The invasive mussels clog pipelines and grates, affecting municipal water supplies, agricultural irrigation, and power plants. Keeping affected infrastructure clean requires regular efforts and can cost millions of dollars.
If the mussels ever reach local waterways, Curtis said, “We would have to raise rates on all water users.”
CPW has partnered with the Bureau of Reclamation to try to keep waterways free of invasive mussels. “That’s the whole premise behind our boat inspection program, which we’ve had since 2009,” Curtis said. Boats and intake motors are inspected at the McPhee Reservoir boat ramp.
He hopes that CPW can ascertain how the veligers got into the Upper Colorado. “They did not go from Highline Lake upstream on their own, so there may be a source upstream,” he said. “I believe that’s what they are trying to find out.”
The presence of zebra-mussel veligers in the Upper Colorado River near Grand Junction has water managers concerned but not panicked.
“It’s a new discovery that’s a bit alarming,” the general manager of the Dolores Water Conservancy District, Ken Curtis, told KSJD.
Veligers are the microscopic larval stage of the mussels. Zebra and quagga mussels are invasive species that originated in Eastern Europe. They were first discovered in North American waters in 1988 in the Great Lakes.
They attach themselves to hard surfaces and can survive out of water for weeks, so they can be spread by boats, other watercraft, and gear such as anchors.
In mid-July, Colorado Parks and Wildlife officials announced that veligers had been found in two locations in the Colorado River upstream of the Grand Valley Water Users Canal Diversion, and in the Government Highline Canal near Clifton. After more sampling, CPW announced in late July that another veliger was found in the Government Highline Canal and two more veligers were found in the Colorado River between De Beque and Grand Junction.
In 2022, adult zebra mussels were found at Highline Lake near Loma, the first time invasive mussels were found in Colorado waters.
Although those sites are not connected directly to the Dolores River, Curtis says it is worrisome that the mussels’ range has grown.
“It expands their range in Colorado and that adds to the risk to other waterways,” he said.
Until the recent discoveries, the location nearest to Montezuma County where mussels had been found was Lake Powell.
“Now we’ve got another population about four hours away,” Curtis said. He noted that so far, however, no adult mussels have been found on the Upper Colorado, only the veligers.
The rapidly spreading mussels have enormous impacts on both ecosystems and infrastructure.
They are filter feeders that clean particles from water, but that can facilitate the growth of weeds because more sunlight penetrates the water. The invasive mussels also consume the microscopic plants and animals on which native species depend, out-competing them.
That alters which types of fish flourish. “Both native fish and trout, or any fish in the lakes, can be affected,” Curtis said. “They can potentially harm the whole food chain.”
Mussels also have what he called an aesthetic impact, as their rotting bodies on shorelines smell bad. And their sharp shells make it unpleasant and hazardous to walk on beaches. “There are all these ripple effects.”
The invasive mussels clog pipelines and grates, affecting municipal water supplies, agricultural irrigation, and power plants. Keeping affected infrastructure clean requires regular efforts and can cost millions of dollars.
If the mussels ever reach local waterways, Curtis said, “We would have to raise rates on all water users.”
CPW has partnered with the Bureau of Reclamation to try to keep waterways free of invasive mussels. “That’s the whole premise behind our boat inspection program, which we’ve had since 2009,” Curtis said. Boats and intake motors are inspected at the McPhee Reservoir boat ramp.
He hopes that CPW can ascertain how the veligers got into the Upper Colorado. “They did not go from Highline Lake upstream on their own, so there may be a source upstream,” he said. “I believe that’s what they are trying to find out.”
