Milfoiled again: Another Colorado barrier to invasive weed falls on the Arkansas River
Colorado Sun
Colorado wildlife officials keep putting up geographic and psychological barriers to the noxious water weed Eurasian watermilfoil, and the voracious invader keeps busting right through.
The fast-growing water floater — the bane of Colorado handlers for nearly two decades — now has been found in Pueblo’s Fountain Lake, near the Interstate 25 and U.S. 50 intersection, and its outlet into the broader Arkansas River. The announcement is the first major spread of milfoil in Colorado since a 2022 invasion of Boulder Reservoir, and opens up the southeastern part of the state to all sorts of trouble.
“Eurasian watermilfoil can quickly damage an ecosystem,” CPW invasive species program manager Robert Walters said, in announcing the find Thursday. One of the few ways to stop milfoil’s relentless spread, wildlife officials have said, is for boaters to be more diligent “about inspecting, cleaning and drying their watercraft.”
The plant hitchhikes in boat propellers, water outlets and other gear as boaters move from lake to lake, or to navigable rivers.
“It is very prolific and can grow up to a foot per week during the growing season,” Walters said. “The species is easily spread by fragmentation, which is when a small piece of the plant is broken off of the main stem.”
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When milfoil reached Boulder Reservoir, Colorado Parks and Wildlife officials said the plant had been first identified as a state invader in 2005 and has since been found in more than 50 water bodies, from major reservoirs to ponds. The dense mats of plants 20-feet long or longer can block habitat for larger fish, and impede sunlight needed to grow other underwater food for fish and wildlife. The mats also interfere with boating and swimming recreation.
Eurasian milfoil is on a list of top Colorado combat targets, a list that also includes zebra and quagga mussels, Asian carp and rusty crayfish.
“While it is unfortunate to confirm (watermilfoil) in any new location, I think it is really important to consider the amount of public waters in the state that continue to be free of it thanks in large part to the preventative measures that CPW has in place,” Walters wrote in an email Thursday.
And he said, “because we have an early detection and rapid response program, we are able to quickly implement response measures, such as the physical removal of the plants that have been detected in the Arkansas River in an effort to prevent continued spread downstream while we evaluate more long term solutions.”