In a bid to streamline efforts to combat invasive species among Western states, the Western Governors’ Association announced a list of top 50 invasive species in the region Thursday afternoon.

“We have needed to identify where the top risks in the West are and what are our priority species so that we can focus the scant resources available to land managers,” the association’s Policy Advisor Bill Whitacre said, adding the list will help prioritize management as a regional, rather than local issue.

An invasive species is defined as a non-native to the ecosystem and whose introduction causes or is likely to cause economic or environmental harm or harm to human health.

The Nature Conservancy estimated that invasive species cost the U.S. economy $120 billion a year, with over 100 million acres – roughly the size of California – impacted by infestations. Data on the cost to Colorado was not available, though the Nature Conservancy noted that ranchers in North Dakota, South Dakota, Montana and Wyoming face more than $144 million a year in losses due to the spread of leafy spurge.

“Invasive species are a clear bipartisan concern that all Western governors and land managers have a stake in addressing,” said Whitacre. “They have economic impacts, social impacts and environmental impacts, and are not contained to any state boundaries … but, up to this point, land managers only have identified the risks of invasives within states.”

Colorado Parks and Wildlife is embracing the effort, especially since the top species on both the aquatic and terrestrial lists have either already invaded or are threats to Colorado ecosystems.

“The issues of invasive species are so broad and widespread that when we work in agency and state siloes, we don’t make progress,” said Invasive Species Coordinator for Colorado Parks and Wildlife Elizabeth Brown.

Tamarisk, a small shrub or tree that hoards light, water and nutrients has drastically altered the Fountain Valley Watershed ecosystem as well as other watersheds across the state and topped the terrestrial list for the West and Colorado. Eurasian watermilfoil, green-leafed plants with reddish-brown stems that grow between 3 and 33 feet in length underwater, were ranked number one on the Western Governors’ Association’s list and are the top weed of concern in the Front Range for CPW, Brown said. The weed was second to whirling disease as Colorado’s top aquatic concern.

Though not on Colorado’s top 10 list, Colorado has its eye on the quagga and zebra mussels. The mussel has decimated wildlife populations, clogged irrigation pipes, wreaked havoc on hydroelectric projects and placed an economic burden in impacted areas across the country.

Adult populations of the mussel have yet to establish in the state, and Brown wants to keep it that way.

“As a headwater state, we are committed to keeping the mussel out of our waterways,” she said, citing the Western Regional Panel on Aquatic Nuisance Species’ boat inspection program as a cross-boundary success story in keeping the mussels out of the state so far.

The program streamlines boat inspection protocol among Western and non-Western states to prevent invasive species from crossing state lines while hidden in the nooks and crannies of a boat. The effort has consolidated resources among state agencies and bolstered the efficiency of states preventing contamination of waterways via invasive “hitchhikers” on boats.

“It’s worked really well to mitigate that one vector of spread,” Brown said. “But the reality is that a lot more species and vectors of spread exists.”

Brown said she believes the Western Governors’ Association’s efforts, starting with the invasive species priority list, will help to further the opportunities for and effectiveness of cross-boundary coordination.

“I believe this will help us and other states to operate with greater efficiency and effectiveness,” she said. “Species know no boundaries or political divisions. They negatively affect wildlife, waterways and the way we use the West as a resource. Parks and Wildlife is very supportive of WGA’s work and know it can make a lot of positive progress on this issue.”