None The Nature Conservancy in Colorado Press Releases Search All Press Releases Aaron Drew Phone: (720) 974-7083 E-mail: adrew@tnc.org

Tamarisk Removal Complete on the San Miguel River

Final Tamarisk Removal Day set for Friday, Oct. 24

TELLURIDE, COLORADO — Oct. 24, 2008 — For the first time, a western river infested with tamarisk is now essentially tamarisk-free. An eight-year effort to control this invasive tree that is clogging river banks across the West is coming to a successful close along southwestern Colorado’s San Miguel River. 

“The impact of these woody invasives is huge -- they rob waterways of their health and make recreational access cumbersome,” says The Nature Conservancy’s Peter Mueller, who directs the North San Juan Mountain Program in Colorado.

Tamarisk is estimated to have infested more than 100,000 acres of land in Colorado and more than 1.6 million acres across the West. Also known as salt cedar, tamarisk consumes massive amounts of water, drying up springs, streams and wetlands. Some estimates are that a single tamarisk removes about 200 gallons of river water a day.

Tamarisk’s dense growth push out native plants and harms wildlife by blocking entrance to the water. The plant is also a nuisance to boaters and fishermen because it narrows streams and chokes out campsites.

The impact of this tenacious competitor is symptomatic of poor health in much of the Colorado River system, where damming and excessive water use by humans has compromised these rivers ability to function naturally. To address these problems, the Conservancy is working with its partners throughout Colorado and other states on a comprehensive strategy to restore the health of the Colorado River system as a whole.

The tamarisk control project on the San Miguel River represents one major initial success in this effort. A 120 mile-stretch of this river – one of Colorado’s most pristine free-flowing waterways – is no longer choked off by the water-consuming plant.

“We’re now seeing the return of the natives – willows, cottonwoods and grasses,” said Mueller. 

The Conservancy-led effort involves volunteers, agency staff and contractors using chainsaws, clippers, heavy equipment and herbicides to remove the thirsty weed. Agencies participating in the grueling work include the Bureau of Land Management, county weed management programs, Marathon Oil Company, the Fish and Wildlife Foundation and the Tamarisk Coalition, a group that coordinates tamarisk control efforts around the West.

On Friday, October 24, volunteers, contractors and others will gather for a final “Save the Natives” work day to cut tamarisk on the last 1.5-mile stretch of infested riverbank near the town of Uravan, south of Grand Junction. The team will also sew seeds of native plants.

Tamarisk-removal efforts have been underway across the West since the 1960s, notably on the Rio Grande and its tributaries in New Mexico, on the lower Colorado near the Mexican border and in Oregon.

In the 1990s, a new biological tool for battling tamarisk was introduced. The U.S. Department of Agriculture imported tamarisk beetles from Eurasia, where they keep tamarisk in check, and after years of quarantine and testing, released them in Utah, Wyoming and Colorado. 

“These beetles are one of the most tested biological agents we have and there’s little risk of them harming other plants,” said Mueller. 

These “natural predators” are slow to work. Only recently have they shown any impact. Now, they are spreading and defoliating tamarisk, and experts hope they will begin to help restore a natural balance between predator and prey.

Over the last three years, the beetles have defoliated a majority of the tamarisk on a 60-mile reach of the Colorado River. From the release site in Utah, the insects have now moved into Colorado and the Dolores River watershed, where Mueller and the project partners will focus their efforts next.

“We’ve been very successful in tamarisk removal on the San Miguel River, but the Dolores will be a more difficult river to tame. It will require a much more involved restoration effort and we’ll need to scale up the number of agencies and groups to work with us,” said Mueller.

Because the Dolores River is dammed, its flood timing is altered which favors tamarisk and other exotic species. 

“On the Dolores we’re talking not just about tamarisk removal, but about restoration of the river way. There we’ll have to look at our water management and do some re-seeding and planting of native species,” said Mueller.

The Dolores is like other western rivers, many of which have been dammed and are in need of major efforts to not only remove invasive plants, but to restore their overall health.

But for now, this Friday’s labor intensive work on the San Miguel should be satisfying. “Those who help with this project will be able to see a big difference in the river from the beginning of the day to the end of the day. When you get rid of this wicked tree, all of a sudden you can see the light, and you can see the river again,” said Mueller.

He added: “We’ll have made this river much nicer and more accessible.”

The Nature Conservancy is a leading conservation organization working around the world to protect ecologically important lands and waters for nature and people. The Conservancy and its more than 1 million members have protected nearly 120 million acres worldwide. Visit The Nature Conservancy on the Web at www.nature.org.