Click here to go to the Invasive Mussel Collaborative website:
This webinar is part of a miniseries on the genomics of invasive mussels hosted by the Invasive Mussel Collaborative. Part one of the miniseries covers the U.S. Bureau of Reclamation’s prize competition “Eradication of Invasive Mussels in Open Water.” The first prize awarded in this competition proposed a novel genetic modification-based method for control…
Sherri Pucherelli: Invasive Mussel Prize Competition
Steve Suhr: Eradication of Invasive Quagga and Zebra Mussels using Engineered Disseminated Neoplasia
FromYale 360 (Jim Robbins). Here’s an excerpt click through for the photos and to read the whole article:
The Colorado River has been dammed, diverted, and slowed by reservoirs, strangling the life out of a once-thriving ecosystem. But in the U.S. and Mexico, efforts are underway to revive sections of the river and restore vital riparian habitat for native plants, fish, and wildlife. Fifth in a series.
From the air, the last gasp of the Colorado River is sudden and dramatic. The pale green river flows smack into the Morelos Dam on the U.S.-Mexico border, and virtually all of it is immediately diverted into a large irrigation canal that waters a mosaic of hundreds of fields — alfalfa, asparagus, lettuce, and other vegetables, their vivid green color clashing against the sere desert. The slender thread of water that remains in the Colorado’s channel continues to flow south, but is soon swallowed up by a sea of sand, far short of its delta, which lies 100 miles farther on.
The Colorado River once surged through the delta during high flows, carrying so much water at times that shallow draft steamboats chugged hundreds of miles up the river into the U.S. with loads of freight. The water in the delta nourished a vast fertile landscape, a fitting end to a river known as the Nile of North America.
“The river was everywhere and nowhere,” the naturalist Aldo Leopold wrote during a 1922 canoe trip to the delta, describing the waterway as it ebbed, flowed, braided, and stalled into pools, nourishing a rich and diverse ecosystem of “a hundred green lagoons,” a “milk and honey wilderness” with thick stands of cottonwoods and willows that provided habitat for hundreds of species of birds. The delta’s marshes, mudflats, and white sand beaches were home to clapper rails, bitterns, mallards, teal, and clouds of egrets.
Bobcats, puma, deer, and wild boar wandered the delta’s forests. Leopold was searching for the jaguar that roamed there, but didn’t see any…
As a natural river, before it was dammed, the Colorado was a massive, dynamic waterway. It flowed from elevations above 14,000 feet in the Colorado Rockies, then dropped to sea level, which meant that it moved at high water with tremendous force, liquid sandpaper carving out red rock canyons. It flooded the desert plains, carving new channels and braids with every inundation. When it receded, it left behind a mosaic of fecund marshes, wetlands, and ponds.
In its natural state, the Colorado had more extreme flows than any river in the U.S., ranging from lows of 2,500 cubic feet per second in the winter to 100,000 cubic feet per second in the summer. In 1884, an all-time historical peak flow reached 384,000 cubic feet per second in Arizona.
But extreme flows are too capricious to support a civilization, so over the past century or so humans have built a network of expensive dams and reservoirs, pipelines, canals, flumes, and aqueducts to tame and divert the flow. Yet these projects also strangled the life out of a once-thriving ecosystem. By design, the river will never again function as a free-flowing stream.
Now, however, experts and environmentalists are rethinking this technological marvel of a river, and looking at ways a natural Colorado can flourish — to some degree, and in some places — with the permission of the engineers. One of those places is in the delta.
The water that flowed in the once-lush delta has been replaced by sand, and the cottonwoods and willows have surrendered their turf to widespread invasive salt cedar and arrowweed. Without the river and its load of nutrients, marine productivity in the Gulf of California — where the Colorado River once ended — has fallen by up to 95 percent. But despite the dismal forecast for the future of water on the Colorado, some conservationists are hoping to return at least a portion of the delta to its former glory.
“We are trying to restore a network of sites that creates a functional ecosystem,” said Francisco Zamora, who manages the project for the Sonoran Institute. “We’ve acquired water rights, but use them for habitat instead of cotton or wheat.”
The delta is one of a disconnected series of restoration projects that government agencies, local groups, and environmental organizations are undertaking along the Colorado. Numerous efforts are focused on tributaries to the main stem of the river, seeking to enhance resiliency by increasing the flow of water and protecting and restoring riparian habitat for fish and other wildlife.
For example, a coalition of groups — including state agencies, nonprofits, and the Arizona cities of Buckeye and Agua Fria — have been removing invasive salt cedar, planting native species, and building levees to reclaim a 17-mile stretch of the Gila River. Invasive salt cedars are a region-wide problem on the lower Colorado, with a single tree sucking up 300 gallons a day. The invasive forest on this stretch of the river uses enough water to serve 200,000 households.
In the upper basin, meanwhile, a number of groups and local landowners are working to restore a 15-mile-long floodplain with globally significant biodiversity on a narrow section of the Yampa River, another Colorado tributary. Called Morgan Bottom, the section has been damaged by deforestation and poor agricultural practices, threatening bald eagles and greater sand hill cranes, as well as a rare riparian forest of narrowleaf cottonwood and red osier dogwood.
But there are limits to how natural the Colorado River can become, especially along the river’s main stem. “We should not kid ourselves that we are making it natural again,” said John Fleck, the director of the University of New Mexico’s water resources program and the author of a book about the restoration of the Colorado. “We are creating an intensively managed system to mimic some nature because we value it.”
Because of the Colorado’s extensive infrastructure, serious disruption of the river’s ecology is inevitable.
Indeed, some of the remaining naturalness on the Colorado is, paradoxically, because of the human-made system. “The geography of the Colorado gives it hope because L.A. and southern California, which everybody loves to hate, guarantee that a lot of water stays in the system through the Grand Canyon,” says Jack Schmidt, a professor at Utah State University and a member of the Colorado River Research Group. “The best friend endangered fish ever had in the Colorado River Basin is that giant sucking sound” of California withdrawing water.
Widespread protection efforts are focused on native fish in the Colorado. The river once was home to an unusual number of endemic fish. But dams, irrigation, and the introduction of bullhead, carp, and catfish did them in. While the upper basin still has 14 native fish species, the lower basin, according to one study, “has the dubious distinction of being among the few major rivers of the world with an entirely introduced fish fauna.”
The Colorado pike minnow — something of a misnomer for a fish that historically grew to 6 feet in length and weighed up to 80 pounds — once swam through the entire system from Wyoming to Mexico. It is now listed as endangered, with two distinct populations remaining in the upper Colorado and the Green River.
The humpback chub lived in various canyon sections, and though once seriously endangered, it has fared better in recent years through transplantation efforts, growing from 2,000 to 3,000 fish to 11,000. Officials say it may soon be taken off the endangered list.
Razorback suckers, once common, are now rare. The bonytail, a type of chub that is one of North America’s most endangered fish, no longer exists in the wild. A handful of these fish exist in hatcheries, and attempts are underway to restock them in the river throughout the basin.
Because of the Colorado’s extensive infrastructure, serious disruption of the river’s ecology is inevitable. Dams trap most of the river’s sediment in reservoirs, which means there is no material to rebuild beaches, sandbars, and important fish habitat downstream.
Dams also deprive the river downstream of nutrients, such as phosphorous and nitrogen, and stratify water temperatures. The native fish in the Colorado adapted to a wide range of temperatures, from cold to very warm. They also evolved to tolerate high flood flows along with extremely dry periods. Now, the water is cold in the summer for miles below the dams, and the humpback chub and other fish that had adapted to a range of water temperatures and flows suffer.
Something called hydro-peaking also has had serious impacts on the food web. Dams generate power according to demand. As people come home from work and switch on the stove, air conditioning, and lights, demand soars and dams release more water to produce power. “Prior to the construction of dams, there were almost no major daily changes in river levels,” said David Lytle, a professor of integrative biology at Oregon State University. When fluctuations in water levels occur, they “can interrupt the egg-laying practices of some species. It’s a serious problem.”
Insects lay their eggs just below the water level, and if levels drop rapidly it can dry them out. A recent study found that below the Hoover and Glen Canyon dams, there was a complete absence of stoneflies, mayflies, and other species — insects that are vital food for fish, bats, birds, and other creatures.
Because of the ecological effects of the Glen Canyon Dam, the Grand Canyon stretch of the Colorado is one of the least productive sections of river in the world. The Colorado here will always be highly unnatural, a novel, human-created ecosystem with some natural elements.
Today, there is a large and growing backlash against dams in America and elsewhere as the immense damages they have inflicted on rivers become manifest. Few dams, though, are as reviled as the Glen Canyon, which was built in 1963 and took 17 years to fill Lake Powell.
Before the Glen Canyon was dammed, those who saw it say it was not unlike the Grand Canyon, with towering walls of red, tan, and ochre. Early Native American sites were plentiful. Environmental activist Edward Abbey decried the dam, and in his novel the Monkey Wrench Gang fantasized about using houseboats packed with explosives to blow it up. In 1981, members of Earth First!, a radical environmental group with a connection to Abbey, rolled a black plastic “crack” down the face of the dam to symbolize its demise.
Removing the dam was part of the reason the Glen Canyon Institute was formed, but activists have now dropped that idea, says Rich Ingebretsen, a Salt Lake City physician who founded the group. Today, he advocates draining Lake Powell to fill Lake Mead, which is downstream and where the need for water is by far the greatest. The “Fill Mead First” campaign would restore a free-running Colorado River to what was once Lake Powell.
“You’d get much of Glen Canyon back,” said Ingebretsen. “A free-flowing river through the Grand Canyon means you’d restore the river — riparian zones, animals that belong there, a beautiful canyon with arches and bridges and waterfalls. Much of that would come back very quickly.” There would also be increased water in the river, he says, because so much of the Colorado is now lost from Lake Powell; scientists estimate that the lake loses three times Nevada’s allotment of water because of evaporation. As levels in Lake Mead drop due to prolonged drought, a growing number of people are taking this idea more seriously.
Paradoxically, two of the Colorado River’s most important wetlands for wildlife are the product of runoff from irrigated farm fields — and are now at risk from a changing climate and agreements to reduce water use.
In the Sonoran Desert of northwestern Mexico, the 40,000-acre La Cienega de Santa Clara wetland was inadvertently created in the 1970s when U.S. officials built a canal to dispose of salty wastewater from agricultural fields in Arizona. As the water began spilling into the desert, myriad forms of life began to appear. Now its cattail-studded marshes and mudflats are considered one of the most important wetlands in North America, home to 280 species of birds — including the endangered Ridgeways rail — on what was once hard-baked desert.
Meanwhile, in California, the Salton Sea was once a shallow inland lake whose levels routinely fluctuated. In 1905, an effort to increase Colorado River flow into the Imperial Valley led farmers to allow too much river water into their irrigation canal, overwhelming their system; for two years the water poured into the 35-mile-long, 15-mile-wide Salton Sea and expanded it.
But as less water becomes available to agriculture and rising temperatures cause more water to evaporate, scientists are concerned that these wetlands will dry and shrink faster than they already have. A 2003 agreement, for example, allows agricultural water in the Imperial Valley to be sent to San Diego for municipal uses. That could cause water levels in the Salton Sea to drop by more than 40 percent, dramatically reducing bird habitat and increasing toxic dust because wetlands would dry out. Local, state, and federal officials have devised a plan — still not fully funded — to restore 15,000 acres of wetlands, at a cost of more than $700 million.
The largest project to restore some semblance of nature to the Colorado River, though, is in the delta. An unusual agreement in 2012 between the U.S. and Mexico, called Minute 319, mandated that the two countries would provide water and funding to revive sections of the delta and release a one-time pulse of 105,000 acre-feet to again connect the river to the delta temporarily. Scientists would then study the effects.
In 2014, for the first time in decades, the river flowed again in Mexico — for eight weeks. San Luis Rio Colorado — once a Colorado River town, but now a dusty desert settlement — became a river town for two months, to the delight of locals, many of whom had never seen the river. The pulse offered a glimpse of what reclamation efforts might look like. “It gave us an idea of how the river behaves, and the best sites for restoration,” said Zamora.
Minute 319 and its 2017 replacement, Minute 323, have funded the restoration of sections of the river. A group of nonprofits — including the National Audubon Society, the Sonoran Institute, The Nature Conservancy, and a Mexican group called Pronatura Noroeste — is working on a project called Raise the River to revive a significant swath of the delta.
In 2008, the group secured rights to 1,200 acres along the desiccated river channel. Since then, local residents have torn out acres of salt cedar and planted irrigated fields of cottonwood, willow, and other endemic species — more than 200,000 trees in all. A small supply of water mandated by the treaty, along with excess water that flows off of irrigated fields, have been dedicated to the restoration.
On a recent visit, I joined Zamora and botanist Celia Alvarado on a short boat ride to Laguna Grande, a 6-mile section of restored river and estuary. We skimmed across still water the color of weak tea, minnows darting away from our paddles. Thick groves of cottonwoods and willows lined the river. Zamora remarked that bobcats and beaver lived there now, along with blue grosbeaks and yellow-billed cuckoos. “Impacting the target species is key,” he said.
And what about the jaguar? I asked. It has not returned, he said. Will it come back?
“Yes,” said Zamora, smiling. “Someday. If they allow me to introduce them.”
Here’s the release from Colorado Parks and Wildlife (Joe Lewanowski):
In order to keep destructive quagga and zebra mussels out of lakes and reservoirs in Colorado, boaters will help to provide crucial funding for the state’s Aquatic Nuisance Species Inspection Program starting in 2019.
“Colorado is one of just a few states in the country that doesn’t have an infestation of adult zebra or quagga mussels in any of its waters,” said Elizabeth Brown, invasive species program manager for Colorado Parks and Wildlife. “That’s directly attributable to our watercraft inspection and decontamination prevention program that’s been in place since 2008.”
Earlier this year, the Colorado General Assembly approved a bill that requires those who operate motorboats and sailboats on waters of the state to purchase an ANS stamp annually. The cost of the stamp for Colorado residents is $25. For boaters coming to Colorado from other states or provinces the stamp will cost $50. The stamp fee is separate from the annual boat registration permit but will be included in the cost of registration for in-state boats. The stamp and registration is currently available for residents at CPW offices and the agency website. Boaters coming from other states can buy their stamp online, at CPW offices or at any sales location beginning January 1, 2019.
Mussel infestations cause a variety of major problems. Because mussels consume plankton they disrupt the food web and out-compete sport fish and native fish. Mussels clog infrastructure, including reservoir dams, outlet structures and distribution systems that carry water for irrigation, municipal and industrial uses. Mussels also infest boats and damage engines.
Mussels have caused billions of dollars in damage, especially in the upper Midwest and Lower Colorado River. Nearby states where mussel infestations exist include Utah, Arizona, Kansas, Nebraska, Texas and Oklahoma.
Since the ANS program started in Colorado in 2008, CPW staff and other entities have completed 4.4 million boat inspections, more than 90,000 boats have been subject to decontamination procedures and 195 vessels with confirmed mussel infestations have been intercepted and decontaminated. The threat of boats transporting mussels also appears to be growing: This year 51 boats with adult mussels were found at inspection stations, far more than the previous record of 26 boats in one year.
The new fee will cover half of the cost of the inspection program. The remainder will be paid by CPW and a variety of stakeholders, including federal agencies, local governments, water providers and other partners.
“We appreciate that Colorado boaters have been very cooperative with CPW on the ANS inspection program. And we all need to continue to be vigilant,” Brown said.
U.S. Fish and Wildlife Service biologists counted 50 yearling razorbacks during a recent survey in the upper Colorado River Basin — the result of water releases in 2016 and 2017 from the Navajo Reservoir aimed at helping the fish, agency officials said this week.
Federal operators of the reservoir let out 5,000 cubic feet of water per second for 50 days, more than doubling regular flows in the San Juan River. This increased flow created nursery pools, the habitat razorbacks and three other endangered native fish need to spawn and survive.
Saving razorbacks and other fish “is going to be totally dependent ” on putting more water into rivers, said Tom Chart, director of the Upper Colorado River Endangered Fish Recovery Program, a 25-year, $360 million government-run rescue effort.
“We’re not going to be able to restore the natural hydrological conditions. We understand that,” Chart said. “But we can recreate conditions that help young fish much more regularly.”
Yet the intensifying climate shift toward heat and aridity in Southwestern states, combined with population growth, constrains biologists’ push to put more water into rivers for environmental purposes. No water could be released this year from the Navajo Reservoir, which straddles Colorado and New Mexico and holds 1.7 million acre-feet, Bureau of Reclamation engineer Susan Behery said. Probably none will be spared next year, either, because water managers are prioritizing storage after a near-record low snow year left the reservoir half full.
Raising, stocking razorbacks
For more than 30 years, federal biologists responsible for emergency rescues of endangered species have relied on raising razorbacks in hatcheries and copiously stocking them into Colorado River tributaries. Razorbacks evolved in wild free-flowing rivers, enduring for millions of years, until widespread dams and diversions reduced and regularized nature’s fluctuating flows. The razorback had nearly blinked out by 1980 with only 100 survivors — weakened by the disruption of flows and attacked by non-native predators such as bass, walleye and pike that state wildlife agencies have introduced for recreational sport fishing…
Federal survey crews counted the 50 yearling razorbacks along the San Juan River downriver from the Navajo Reservoir. That’s the most fish counted since the surveys began two decades ago. Fish and Wildlife Service biologists calculated that this many yearlings could mean there are thousands of razorbacks along a 180-mile stretch of the river before it reaches Lake Powell.
Navajo tribal biologists have embraced the effort to save razorbacks and other imperiled native fish. A Navajo team this year helped move 300 razorbacks over a barrier for spawning while weeding out non-native predators.
“We are trying to preserve the razorback for our future generations,” said Navajo fish biologist Jerrod Bowman. “So that our kids can see razorbacks. … Our numbers are really looking great.”
“Far from the self-sustaining populations”
The problem with officially upgrading the status of fish, Bowman said, is that just the presence of yearlings may not establish that a species has become self-sustaining as required. Razorbacks usually don’t reproduce until they’re at least 2 years old. Adults can live up to 40 years.
Under President Donald Trump, federal wildlife officials have faced pressure to upgrade and de-list endangered species when scientists still aren’t certain about survival, said ecologist Taylor McKinnon, a public lands campaigner for the Center for Biological Diversity.
Here’s the release from the Bureau of Reclamation (Peter Soeth):
Bureau of Reclamation Commissioner Brenda Burman announced today that Reclamation has selected three submissions for its prize competition seeking ideas to eradicate mussels in open water. Steven Suhr and Marie-Claude Senut will receive a full award of $80,000 for their idea while Wen Chen and Absar Alum with Stephanie Bone will each receive $10,000.
“Providing water managers with new tools to control invasive quagga and zebra mussels is an important part of protecting infrastructure and ecosystems,” Commissioner Burman said. “Reclamation is committed to working with our partners to prevent the spread of quagga and zebra mussels in the West.”
The prize competition was a theoretical challenge and sought innovative solutions to eradicate invasive quagga and zebra mussels from large reservoirs, lakes and rivers in a cost-effective and environmentally sound manner. Invasive mussel infestations pose a significant logistical and economic challenge for local communities, recreationists and water managers. There is no practical method available today for the large-scale control of invasive dreissenid mussel population once they become established.
Steven Suhr and Marie-Claude Senut, founders of Biomilab, LLC, proposed using genomic modification to induce a lethal malignant hemic neoplasia in mussels that can be transferred from one mussel to another by proximity. They suggested utilizing the CRISPR/cas9-mediated genome modification to target the function or expression of endogenous dreissenid mussel p53 or telomerase reverse transcriptase genes, or to introduce the viral SV40 Tag gene. This submission for the prize competition received $80,000.
Wen Chen, a research scientist at Harvard Medical School, proposed utilizing single stranded DNA/RNA oligonucleotide-based aptamers to target the modified amino acid 3,4 dihydroxyphenylalanine (DOPA) or dreissenid specific foot proteins to interrupt attachment, eventually leading to mussel mortality. The use of aptamers to target DOPA and foot proteins to interrupt mussel settlement is a novel idea and received $10,000.
Absar Alum of BioDetek with Stephanie Bone proposed genome modification to develop male mussels that produce sperm containing a light triggered optogenetic switch to drive upregulation or downregulation of cyclin-b expression resulting in death of the fertilized egg. This strategy relies on sunlight penetration into the upper portions of a water body to turn on the optogenetic switch in free-floating, transparent developing eggs and embryos. It was found to be a novel idea and received $10,000.
A total of 238 solvers signed up to solve this challenge and more than 100 solvers submitted solutions. Of those solutions submitted, 67 were deemed viable and were judged. Reclamation collaborated with the U.S. Geological Survey, the U.S. Army Corps of Engineers, and Molloy & Associates on this prize competition. To learn more about this prize competition please visit https://www.usbr.gov/research/challenges/mussels.html.
The results of this prize competition will support a broader effort by the federal government, as well as work by the Western Governors’ Association, western states, and tribes to protect western ecosystems, water infrastructure and hydroelectric facilities from invasive mussels. To learn more, please visit https://www.usbr.gov/mussels.
The Dolores River shows us what’s at stake in the fight to protect the American West — Conservation Colorado
Photo via the Sheep Mountain Alliance
Dolores River watershed
Dolores River south of Lizard Head Pass
Dolores River near Bedrock
Dolores River above Dolores
Dolores River Canyon near Paradox
FromThe Walton Family Foundation (Peter Skidmore):
In the Colorado River Basin, RiversEdge West leads a coordinated effort to restore critical habitat
Doug King’s family has been ranching the lands around the Dolores River in Southwest Colorado since the 1930’s. “It’s beautiful−I call it John Wayne country,” Doug says, proudly. “I’m the third generation on the land, my son will be the fourth generation, and his son will be the fifth.”
Over the decades, Doug experienced firsthand the steady, relentless creep of invasive plant species like tamarisk and Russian olive and its impact on the land he has cared for his whole life. The damage has been extensive, threatening the larger riparian—or river bank—habitat that in the Colorado River Basin ultimately supports more than 40 million lives across two nations.
As the unwelcome vegetation pressed in on essential farmland and fish and wildlife habitat, Doug and many others in the region understood it was time to lock arms and push back.
Originally conceptualized in 1999 to discuss strategies for addressing invasive plant species along rivers in western Colorado, the then-named Tamarisk Coalition was fueled by a desire to shape a landscape-scale solution. The group had observed that conventional site-by-site eradication simply wasn’t able to move quickly enough.
“People were getting grants to do five acres or half a mile” of tamarisk removal, recalls Tim Carlson, the coalition’s first executive director. “That wasn’t going to solve the problem. We started with a bold approach: If we were going to solve this problem, it’s got to be a regional solution.”
The introduction of the tamarisk is a story of unintended consequences. Long thought to prevent erosion along the banks of western rivers, its presence was so valued in earlier days that Boy Scouts would receive badges for planting it. But the persistent shrub with scale-like leaves took to its adopted habitat like a parasite, displacing native vegetation.
Restoring and sustaining the overall health of the Colorado River Basin has been a primary goal of the Walton Family Foundation’s Environment Program since its inception nearly a decade ago. And, the program’s first grant to the Tamarisk Coalition in 2009 supported its restoration efforts along the San Miguel and Dolores river systems. Gradually, the foundation expanded its support to also include work along the Escalante, Verde and Gila systems.
“We have a great relationship with the foundation where we present innovative ideas, and they help us scale up these efforts. The investment affects a vast landscape, bolsters our work and has helped us promote best practices to other organizations,” says Cara Kukuraitis, outreach and education coordinator for the organization now known as RiversEdge West.
The organization changed its name in 2018 to reflect its broader work in Western riparian areas and the surrounding communities. But it retains its unique and core operating model—to facilitate collaboration and information-sharing across diverse groups and individuals to accomplish riparian restoration at a larger scale than any one partner can attain on its own. As a result, RiversEdge West now supports 20 ambitious multi-stakeholder partnerships encompassing federal, state, and community organizations throughout the American West, teaching best practices to over 300 local public and private restoration organizations and successfully restoring some 11,500 acres—and counting—of riparian habitat.
The state of Colorado is among the group’s core partners.
“Our relationship with RiversEdge West has allowed Colorado Parks and Wildlife to more effectively meet our mission of improving the wildlife habitat within the state,” explains Peter Firmin, manager of the James M. Robb-Colorado River State Park.
“The networking and training opportunities provided by RiversEdge West allow us to leverage intellectual and financial resources to improve habitat along the Colorado River. As a group, we are able to accomplish more than we could as individuals.”
The work of RiversEdge West and its growing network is bolstered by an array of technical tools. For example, a multi-partner geodatabase stores and shares data with land managers, so they can see how their projects connect and positively impact the landscape over time.
“The data helps us establish and measure progress against quantitative goals, so the project can jump from removing tamarisk by just cutting trees to collecting data on the extent of the problem and promoting ways to encourage the ecosystem’s overall health,” says Cara.
It is a testament to the organization’s enduring value that its annual conference attracts upwards of 200 representatives from Colorado, Arizona, Nevada, New Mexico, California, Texas, Kansas, Oklahoma, Utah and Mexico to connect on riparian restoration science.
The organization also is working to convey the broad importance of these efforts through its ongoing “Riverside Stories” web series, which tells the personal stories of people who call this land home and are working to restore this habitat for future generations. Among them is Doug and his family.
“I have a theory that we should leave the land better than how we got it,” Doug notes in sharing his story. “The Colorado River is soon going to be the most important resource in the West. We are just caretakers. You are only going to be here 50-60 years, and then somebody else is going to have this land.
The tamarisk, which was brought to the U.S. from Eurasia in the late 1800s for erosion control, windbreaks and decoration, is much detested. Since its introduction, tamarisk – also known as salt cedar – has been blamed for choking waterways, hogging water and salting the earth as its range expands, driving out such native trees as cottonwood and willows. In Palisade, Colorado, a state lab is breeding beetles whose sole purpose is to destroy tamarisk. At one point, the University of Nevada published a poster about the plant titled WANTED – Dead, Not Alive!
“There’s been a concerted effort to demonize tamarisk,” said Matt Chew, a historian of invasion biology at Arizona State University’s School of Life Sciences. But he thinks this war is aimed at the wrong enemy.
The tree, he said, is a scapegoat for our struggle with something much bigger and messier than weedy fields: our relationship with water in the West.
The tamarisk has a reputation for hogging water – but is it warranted?
“This is one of the constant counts against tamarisk – that it’s wasting water,” Chew said. “That particular idea got started in the late 1930s and early 1940s for a very particular reason.”
Back then, Chew says, the Phelps Dodge Corp. wanted to expand its copper mine in Arizona, but it didn’t have the water it needed for the additional mining and processing. All the water rights to a nearby creek and river had been allocated.
“What they needed was an excuse to say there was more water in the rivers so that Phelps Dodge could have more water,” Chew said. “So, where are they going to get more water?”
Phelps Dodge inspected nearby water sources and found lots of tamarisk growing along the banks, Chew said. Mine officials rationalized that if they could prove the tamarisk was draining river water, he said, the mine could potentially get the rights to the “extra” water available by killing tamarisk.
“Phelps Dodge did a bunch of experiments which were later picked up by the Agriculture Department,” Chew said, adding that Phelps Dodge ended up getting its water rights through other means, but the tamarisk’s image was destroyed.
As Chew writes in the “Journal of the History of Biology,” “with water shortages, economic development during the Depression and copper mining for national defense during World War Two, federal hydrologists moved quickly to recast tamarisks as water-wasting foreign monsters.”
Since then, researchers have shown that the tree doesn’t use more water than native riparian vegetation, including cottonwoods.
To make matters worse, big changes were occurring in the 1930s and ’40s in the way that water was being moved through the West. Dams and diversions were changing the patterns of flooding, patterns that used to be in sync with the reproductive cycle of more sensitive native plants, such as cottonwoods.
“To some extent, the way we were managing Western rivers actually created a giant tamarisk housing project,” Chew said. If the tamarisk is a monster, he said, it’s because we created it.
“If you want good, old-fashioned 17th-century riparian areas in the western U.S.,” Chew said, “you can’t take all the water out of the river. You can’t have big irrigated fields. You can’t have huge cities.”
Anna Sher, an invasive species biologist at the University of Denver and author of the book “Tamarix: A Case Study of Ecological Change in the American West,” agrees that Tamarix (the species’ genus) isn’t all bad.
Yes, Tamarix can create saltier surface soil that retards other vegetation, and its dense wood can fuel more intense fires. Sher even has heard that a boater drowned in Arizona because rescuers couldn’t get through the dense thickets of tamarisk crowding the shore in time to help him.
But, she says, “I certainly do not hate this plant.”
It provides nesting spots for the Southwestern willow flycatcher, for example, and she says it’s entirely possible for the trees to be a part of the landscape without completely taking over.
“It’s only behaving badly because of the way that we’ve managed our rivers,” Sher said.
Although the way we manage our rivers isn’t going to change anytime soon, Sher sees hope for restoring the landscape. It’s called the Field of Dreams hypothesis.
“The Field of Dreams hypothesis predicts that when you remove the invasive species, there’s an opportunity for the desirable species to come in,” she said.
Initially, Sher and other ecologists suspected the hypothesis was a pipe dream.
“But after doing surveys of hundreds of sites throughout the American Southwest, we can see that, on average, native species will come back and they’ll come back proportionally to how much tamarisk has been removed,” she said. “More tamarisk taken out, more native plants can come in.”
There are two conditions required for successful restoration. First, there has to be enough water in the rivers and streams to supply the new vegetation. Second, the public has to remain open to what native plants might come back. They might not be the cottonwoods and willows people hope for.
“It’s a new game now with Tamarix here and with the water needs that we have now,” Sher said, and humans will have to get used to plants that can handle the landscape as we’ve shaped it.
Those plants might be drought-adapted shrubs and grasses instead of picnic-worthy trees. And they will most certainly have a tamarisk or two as neighbors.