The invasive Arundo reed threatens Arizona rivers. Why getting rid of it is so difficult
As he paddled his boat down the Wild and Scenic stretch of the Verde River, Robin Silver began to feel like he was navigating through a tunnel. He looked to both sides, to the banks of the river, and the only thing he could see were enormous walls of giant reeds.
He felt trapped.
Silver had embarked on a five-day journey by boat from Childs to Sheep Bridge, traversing six or seven miles each day and camping during the cold nights of the early spring.
"I came along with a group of kayakers because I wanted to see if there was any recovery in the 20 years since we removed the Fossil Creek Dam," Silver said. Fossil Creek is a tributary of the Verde that flows down from the Mogollon Rim.
As a Center for Biological Diversity co-founder, Silver has been actively involved in numerous environmental recovery efforts, including one to protect the Verde and its tributaries from cattle grazing. That work was part of why he took the rafting trip to monitor the recovery within the riparian area.
What he found were 30 miles of river invaded not just by cows but by a giant, non-native reed. It's known as wild or river cane, or just giant reed, but its scientific name is Arundo donax.
It is a tall grass, similar in shape to bamboo, that can grow up to 30 feet tall. Its poles grow very close to each other, forming compact clusters of impenetrable masses.
When its fibrous roots are anchored in or near water, the dense stands of Arundo can collapse over the river in the current, making it very difficult or even dangerous for boaters to navigate the channel.
"We're worried about getting caught up in shoots where the water's going through 30-foot-high bamboo," Silver said. "That's not wild and scenic. That's wrong."
But the risk goes deeper than safety. Environmental activists want to eradicate the reed because they say it will choke riparian habitat, threatening the native plants and wildlife that rely on the desert waterways. It can also become a fuel for wildfires.
Fighting it requires persistent work along hundreds of miles of waterways, and for others, the value of the plant is tied to cultural traditions, such as crafting musical instruments, something they say is worth preserving.
What is Arundo and why is it a threat?
Arundo donax is considered an invasive plant due to its impact on ecosystems. It outpaces native vegetation in growth speed and density, encroaching upon and diminishing its vitality.
This plant consumes three times more water than the others around it. If it can't get enough water, it rapidly dries out and becomes highly flammable, exacerbating the frequency and intensity of wildfires.
As a result, local wildlife suffers from habitat loss. While larger animals encounter challenges in accessing water sources along riverbanks, songbirds are unable to nest on this reed.
"Many of the birds that live along the river depend on insects or small mammals like rodents that live on the ground. And when you can't see the ground because you've got 30-foot-tall bamboo, you can't live there," Silver said.
Unlike cottonwood, which grows along the water's edge and is displaced by the giant reed, Arundo donax offers minimal shading. This leads to elevated water temperatures, decreased oxygen levels, and diminished aquatic habitat quality.
Regarding human use, "long term, it's gonna affect the water supply for Phoenix," Silver said. The metro area draws heavily on water from the Salt and Verde rivers.
Riparian health: Why river advocates say Arizona's upper Verde should earn 'Wild and Scenic' protections
Arundo on the Tanque Verde in Tucson
In Pima County, an organization is working with a crew of volunteers to clear out Arundo from the creeks northwest of Tucson.
Jim Washburne, project coordinator of the River Run Network's Arundo Removal Effort for Watershed Management Group, has been on a 12-year quest to eradicate Arundo. Ten years ago, he started the project to remove the invasive reed from Sabino Creek.
"We worked there for three or four years, and it's virtually gone from Sabino Creek now," Washburne says.
The crew is now working to eliminate the reed from Tanque Verde Creek, an effort that's been ongoing for the past three years.
About twice a month, on Saturday mornings, Washburne guides 15 or 20 volunteers of varying ages along a path through the brush until they reach the work site on the edge of a seasonal water flow.
"Our method here is mostly hands-on, physical labor," Washburne says. "After doing this for over a decade, I've found that digging out the roots by hand is the most effective in the long run."
He provides basic tools to those who do not have their own: loppers to trim the branches and pickaxes to extract the rhizomes — the subterranean stems that produce the root systems — from the ground.
Some chemical treatments work well for a year or two, Washburns said, but then deeper roots tend to sprout.
"Also, you don't want any horses or dogs or anything to lick it and have a health impact," he says. "So, it takes a little bit longer, a little bit more effort, maybe. But, we found this the most effective way to get it out permanently."
The next stage is to dig out the roots with a mini excavator or backhoe and carry them up above the flood level to dry out.
"We'll leave those roots to desiccate. It can take over a year for them to fully dry out," Washburne says. "We must be persistent and follow up with it."
Lauren Knight, River Run Network program manager at Watershed Management Group, says they have restored and removed Arundo completely from about 55 acres of riparian area just in the Tanque Verde Creek.
"Without volunteers, we would not be able to do this work. If it was just Jim and me, we would still be way farther upstream," Knight says. "People get really excited about this effort. And it's a lot of hard work that I think people are really proud of."
The group has started stage two of the project, which involves revegetating the water banks by planting native riparian plants and trees like cottonwood and seep willow.
The Watershed Management Group is able to do the work in part with grants it has won from the Arizona Water Protection Fund and the Arizona Department of Forestry and Fire Management.
Non-native vegetation: How removing invasive buffelgrass from Arizona forests can reduce wildfire threats
State money helps remove invasive plants
The Department of Forestry and Fire Management awards 10 grant applications for invasive plant removal every summer.
The department partners with eligible entities like state government, cities, counties, Native American tribes and nonprofit organizations.
"The Watershed Management Group has a pretty good approach, using a lot of volunteers from the community," said Willie Sommers, the department's invasive plant program coordinator. “It's a way to give back to their community and the environment."
It's an opportunity for people interested in learning more about the natural environment, helping reduce these invasive plant populations, enjoying some outdoor time, and getting to meet other people, Sommers said.
Friends of the Verde River has also applied for and received several grants from the department to control invasive plants.
Entities must submit a project plan that includes not only the removal of the plants but also their disposal. In this regard, Sommers says he would like to receive more creative ideas for repurposing or recycling the reeds.
Most organizations have few such collaborations, which means if they don't dispose of the Arundo in a dumpster, they typically use it as mulch for landscaping projects.
Arundo is music to the ears of some people
Although many try to get rid of Arundo, the reed has been used in construction, crafting fences or roofs, making walking sticks and fishing poles, creating musical instruments, and, more recently, as a potential biofuel source.
The Watershed Management Group has partnered with the School of Music at the University of Arizona in the past, supplying them with reeds for making flutes and other musical instruments.
Indigenous tribes in Arizona traditionally have crafted flutes made from different canes, said Aaron White, a Native American musician and flute maker.
"First, they were used for hunting, mimicking the sounds of birds and high-pitched animals, but then they turned to ceremonial instruments," White said.
White is a songwriter and Grammy nominee whose music was recently part of the soundtrack of the Emmy-honored film "Lakota Nation vs. the United States." He's also a lecturer on music and gives workshops where he teaches how to make flutes out of Arundo reed.
White plays other instruments, such as guitar, keyboards and percussions. Yet, his flute has a soothing effect on his audience, who grow quiet as he plays the hypnotic sounds.
"I just can't reiterate how important it is to the culture and history," White says. "It's just been around for so long, you know? It has so much history. And I still think a lot of people don't really realize how that is."
It is not that White opposes keeping watersheds healthy. His message is more about carefully considering how these reeds are used. He says actions on the rivers will significantly influence the preservation of cultural values.
Green is the Verde: How an Arizona river became a water conservation success story, for now
Who will take control of the Arundo donax in the Verde River?
The Friends of the Verde River provide services to private landowners, as well as state and federal land managers, in the Verde Valley. They lead restoration projects, such as removing invasive plants from Oak Creek and Fossil Creek.
The local nonprofit formed the Verde Watershed Restoration Coalition in partnership with other agencies and organizations to intensify efforts and address this situation.
The four Forest Services in the Verde watershed, the Kaibab, Tonto, Coconino and Prescott, are all partners in this alliance.
Tracy Stephens, program director with Friends of the Verde River, said the group is starting to work on a project plan that will begin this fall. It will focus on the river's Wild and Scenic stretch.
"From Beasley Flat, we will try to address those concerns with the invasive plant species similar to what we've done throughout the rest of the watershed," Stephens said.
Andy Pigg, a forest botanist with the Coconino National Forest, said agency works from the top down the watershed since it's the most effective way to avoid re-sprouting.
"If a piece of Arundo breaks off and floats downriver, it can reroot there and grow," he said.
Like Silver, Pigg went on a kayaking expedition, this one from Beasley Flat to the Horseshoe Reservoir. He observed the amount of Arundo growing on the riverbanks and noticed some phragmites as well. Phragmites, also known as common reeds, are similar in shape to Arundo.
"We want to make sure to have the right identifications to treat the right species," Pigg said.
The removal project involves several stages. The first will include surveying and planning the trip's logistics, followed by treating, measuring, and monitoring the treatment's success. Maintenance is the final step.
If they decide to use herbicides, they need to plan for containment so the chemicals don't reach the water, and would need approval for this option.
Different methods could be implemented. The Animal and Plant Health Inspection Service has approved using wasps to control the giant reed in Texas.
Still, in Arizona, Pigg said the Forest Service's approach is to carefully evaluate any biological control agent to ensure it will not negatively affect or lead to a decline in another species.
Friends of the Verde River said they work with the Forest Service. In addition to funding the project that will start in the fall, "they're quite active in assisting us with our work and providing subject expertise," Stephens said.
"Also, we don't have the boats and the river gear. The national forest will assist our cruise on those river trips to implement that restoration work," Stephens said, "that's something that I don't think we could accomplish without their cooperation and expertise and equipment."
The Friends of the Verde River, in collaboration with the U.S. Forest Service, is still in the early stages of planning that work. Nevertheless, the group is promoting volunteer opportunities for people who want to help. Anyone interested can sign up on their website.
Another way to help is to use the iNaturalist app to report any invasive plants encountered while recreating, floating or hiking in the Verde watershed. Stephens said the Friends of the Verde River monitor these reports constantly.
'It will be very difficult to remove'
A month has passed since his boat trip, and Robin Silver returned to hike along the banks of the Wild and Scenic section of the Verde River to see how much the Arundo is taking over and take photos of it.
To his surprise, he observes a significant drop in water current compared to his previous visit. This change is evident from the debris caught in the branches of the remaining trees lining the banks and the Arundo stalks.
He also notes that even though the currents were strong enough to knock some branches off the trees, the Arundo remained steady and firmly rooted along the riverbanks.
Silver has mixed feelings. On the one hand, it's good to see fewer cattle grazing along the Verde River. But on the other hand, "it's frightening that once Arundo takes hold, it will be very difficult to remove," he says.
Trilce Estrada Olvera writes about environmental issues for The Arizona Republic and azcentral. Send comments and story tips to trilce.estradaolvera@arizonarepublic.com.
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This article originally appeared on Arizona Republic: Arundo donax threatens Arizona's waterways, but it's hard to control
