GSPI News Editor
When wildlife lovers look along the Colorado River near Silt, they see towering cottonwood trees housing nests from which herons survey their domain.
It’s a threatened domain, however, under attack by an invader that is drawing increasing attention from local to federal governments.
The tamarisk, a water-loving plant imported from Eurasia, has been gradually taking over riverbanks since its introduction to the Colorado Plateau early in the 20th Century. Recognized for years as a scourge of river ecosystems, the thirsty tamarisk is now a prime target for eradication due to the recent drought.
Steve Anthony, vegetation manager for Garfield County, can list any number of reasons for focusing more efforts on eradicating the woody, shrublike tamarisk plant.
Even with the focus on water waste, tamarisk invasion into cottonwood habitat, home to herons and eagles, remains a pressing concern for Anthony.
“It’s been documented that we’re losing that. That’s being displaced. … Nowhere is that more evident than between Silt and Rifle,” he said.
Forests of tamarisk, accompanied by another invasive species, the Russian olive tree, are taking over as old cottonwoods are dying.
“We’re not seeing the new cottonwoods coming in,” Anthony said.
The tamarisk was introduced as an ornamental plant and to control erosion. Like many invasive species, it fared far better than expected.
Its extensive root system enables it to thrive even during drought, at the expense of nearby native plants that it crowds out.
Also known as salt cedar, tamarisk increases soil salinity, making it harder for neighboring plants to survive and adding to the problem of salt in the Colorado River.
It also increases fire danger along rivers, yet can’t be killed by burning.
Tamarisk reproduces rapidly, according to a tamarisk fact sheet on the state of Colorado’s Web site. A mature tamarisk shrub can produce 250 million seeds per year. The small seeds are easily dispersed by Colorado’s winds and streams, and germinate in just 24 hours. Within a few weeks, the tap root penetrates deep into the soil or sand.
Tamarisk leaves contain little nutrition for wildlife, and the plant harms animals by eliminating the native vegetation they rely on for food and shelter.
The tamarisk also steals a precious commodity. One large tamarisk can use as much water in a single day as a family of four.
Anthony said a typical young tamarisk can consume 200 to 300 gallons per day.
“If you have an acre of tamarisk, you can imagine the math involved here. It’s pretty significant,” he said.
U.S. Rep. Scott McInnis, R-Grand Junction, did the math.
Then the longtime advocate for Western Slope water introduced a bill early this year to allocate $1 million for Mesa State College to conduct tamarisk research. The college also would provide technical and education assistance to governments and individuals working to control tamarisk.
A U.S. Senate bill introduced by Sen. Ben Nighthorse Campbell, R-Colo., goes even further. It would allocate $20 million, earmarking 90 percent for eradication and habitat rehabilitation.
In his bill, Campbell states that tamarisk occupies between 1 million and 1.5 million acres in the West, and uses 2 million to 4.5 million acre feet of water per year. An acre foot is 325,851 gallons.
The water used by tamarisk stands in the West could provide for 20 million people or the irrigation of more than 1 million acres, he contends.
Colorado Gov. Bill Owens has also jumped into the tamarisk battle. He ordered the state departments of Natural Resources and Agriculture to work with other cooperating state, federal and local agencies, with the goal of eradicating tamarisk on public lands in 10 years.
Owens gave the Department of Natural Resources a year to outline a plan for achieving this goal.
In Garfield County, Anthony and vegetation managers for federal land agencies welcome these new legislative and administrative efforts. They look forward to any possible help in a battle that they’ve been fighting with some success, but on a limited scale, for years.
“Anything that has to do with getting funding for nonnative species control is good news from our perspective,” said Wayne Nelson, noxious weed coordinator for the White River National Forest.
“Extra funding would be great,” agreed Richard Barry, Nelson’s counterpart in the U.S. Bureau of Land Management Glenwood Springs Field Office.
Anthony was particularly impressed by Owens’ order.
“That was real significant when he did that,” Anthony said.
Research funding is always helpful, Anthony said. But by and large, he said, experts have a good idea of what works in terms of tamarisk eradication and restoration of riparian habitat. He believes the biggest need is for funding to carry out the job.
General weed control can cost $100 an acre, said Anthony. The cost of eradicating the pesky tamarisk can cost up to $2,000 an acre when workers use chain saws to cut it down.
Anthony and Nelson have spent time grubbing out tamarisk, and say it is hard work.
A few years ago, Nelson worked on a project to rid tamarisk from the Forest Service portion of Glenwood Canyon, roughly from No Name to Bair Ranch.
“We cut it out and treated it on our portion,” he said.
The stumps must be immediately treated with herbicide; simply cutting down the tamarisk won’t kill them.
“It’s super-intensive, a lot of labor. But it looks pretty successful so far,” Nelson said.
Nelson said the BLM also treated tamarisk above Bair Ranch.
But tamarisk “has really gone wild” upstream of Glenwood Canyon, he said.
Even within the canyon, the battle against tamarisk isn’t over. There is plenty of seed in the soil, and the Colorado River continues to carry seed downstream, Nelson said.
“So it’s going to take plenty of maintenance,” he said.
Said the BLM’s Barry, “I’m assuming probably next year or the year after, we’re going to have to do some follow-up in those areas, tamarisk being the way it is.”
Anthony is chasing down tamarisk control in other spots, including lands in Glenwood Canyon held by the Colorado Department of Transportation. He’s also worked with Eagle County along the bike path near Bair Ranch, and with the U.S. Department of Energy at the former uranium ore processing site west of Rifle.
It’s all a good start, Anthony said, but he looks at the control of weeds such as tamarisk as a long-term job.
“You’ve got to get started on something and keep plugging away on it,” he said.
He also thinks tamarisk control is only half the battle along riverbanks. Russian olive is just as dominant as tamarisk from New Castle west along the Colorado River, he said.
“It doesn’t do much good to work on one without getting rid of the other. They both do some damage to the ecology of the area in different ways, but they’re both highly invasive species,” Anthony said.
Tamarisk and Russian olive have spread beyond the Colorado River along tributary streams.
Although there is a lot of tamarisk on public land, there’s even more on private property, Anthony said. He also sees Russian olive trees lining ditches, sucking up water intended for agricultural irrigation.
For this reason, he believes any truly helpful legislation will provide some cost-sharing for landowners to remove these unwanted plants.
Garfield County already has such a program, which provides 50 percent cost reimbursement for noxious weed control.
Said Anthony, “This is a good program that has been a partnership between the county commissioners, who fund the program to the tune of $25,000 this year; the soil conservation districts, who administer the program; and residents of the county, who control the weeds on their property.”
Contact Dennis Webb: 945-8515, ext. 516
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