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Volunteer WeedSpotters


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ESWA WeedSpotter Team

Fighting those pernicious NOXIOUS WEEDS and helping Native Plants thrive!

The WeedSpotter team continues to grow to identify and fight the weed infestations that threaten the Wilderness. Each summer we host several weed pull and native seed gathering sessions. Join us for a few hours with friends, protecting native plants and wildlife.
For dates of specific projects, consult the ESWA calendar[links to calendar] on the Home Page. For more information on the ESWA WeedSpotter program send an email to


Containing a Biological Wildfire!

“Like an unwanted wildfire, noxious weeds can drastically affect wildland plant and animal communities, damage watersheds, increase soil erosion, and adversely impact recreation. However, unlike the temporary negative impacts of wildfire, ecological damage from extensive noxious weed infestations is often permanent. Lands affected by wildfire are self-healing, whereas lands invaded by noxious weeds don’t return naturally to their pre- invasion condition.

Weeds continue to spread and the damage worsens. When considering long-term ecological effects on the land, invasion by aggressive non-indigenous noxious weeds is far more damaging than any wildfire.” – Steven A. Dewey, Utah State University


ESWA WeedSpotter Program Overview 

ESWA has been battling this invasion since 2004. Hundreds of volunteers have spent thousands of hours picking weeds, and more than $100,000 in grants to ESWA (mostly from the National Forest Foundation Ski Area Conservation Fund) have financed professional treatment of weed infestations. ESWA continues to treat, measure and map a dozen major weed infestations. The combination of treatment and measurement will ensure we make progress against these spreading invasive species. 


Our ongoing fight 

Noxious weeds have certainly crossed the borders of areas ESWA is responsible for – Eagles Nest Wilderness, Ptarmigan Peak Wilderness and Holy Cross Wilderness Areas – invading and changing the pristine environment. ESWA is working closely with the USFS to manage infestation. These noxious weeds affect the forest is several ways. Currently there are 37 noxious weeds in Summit and Eagle Counties that endanger our Wilderness. A major part of this program is to locate infestations and to control the spread of invasive plants that are harmful to the forest. 


The ESWA WeedSpotter program concentrates on mapping and assessment of weed infestations by using its volunteers and technology (GPS, Cell Phones, etc.). As we gather clear facts and data on Wilderness infestations, we help focus USFS effort on those areas, raise money to supplement USFS efforts with professional eradication teams (approved by USFS), and volunteer weed pulls (for example, a thistle outbreak miles back a trail). This combination will ensure the Weed program has measurable effectiveness.


For more information on the ESWA Invasive weeds program send an email to For dates of upcoming projects, consult the ESWA calendar on the Home Page.


Current WeedSpotter targets

ESWA will continue treatment in areas that we treated over the past summers: 


• The USFS and ESWA will manage treatment of 8 infested areas: 

o Colorow Creek & Elk Park - Holy Cross Wilderness. 

o Martin Creek Trail Corridor – Holy Cross Wilderness 

o Lake Creek – Holy Cross Wilderness 

o Piney Meadow Creek and Piney Trail – Eagles Nest Wilderness 

o Slate Lakes – Eagles Nest Wilderness 

o Harrigan Creek – Eagles Nest Wilderness 

o Brush Creek – Eagles Nest Wilderness 

o Acorn Creek – Ptarmigan Wilderness 


Also, our Weed Mapping Teams will map out noxious weed infestations, with a partner. Each team member will “adopt an infestation” from a list of targeted weed infestations in Summit and Eagle Counties, then hike to and measure the size of the infestation for USFS records. We need volunteers to measure the infestations before and after (June/July, September) – Join us! 

Should I pick weeds?

Yes and no. Most weeds you see should not be picked because they respond by growing back stronger. Some should not be picked because the native and invasive species are hard to tell apart. 


A couple species can be picked because they are only spread by seed. ESWA is recommending only two types of weeds should be picked – Musk Thistle and False Chamomile. Carry a garbage bag with you, put the weeds in them and carry them out. If the seed heads are left in the wild, they may spread the weed even more! 


See a weed? Take a picture! A major goal of the ESWA Invasive Plant Program is to locate, identify and map out weed infestations. It is important for our program to get an accurate measure of the extent of weed populations in the Wilderness. If you see anything you think is a weed when you are in the wilderness (especially far back in the wilderness), report it to us. This will be invaluable in planning future treatment of weed populations and justify future grant applications. 


If you see suspected weed, report it to us as soon as possible. Since none of us are trained botanists, we’re using a simple procedure. Take a picture with your cell phone and e-mail it to


Cell phone pictures include the GPS location of the picture, and we can use it to add your report to our database. For the best reporting: 

  1. Set your phone so location services are enabled on the camera (before you leave home). 


2) Take pictures of the suspected weeds from the top (flowers) and side (stem and leaves). If there is a big area of the weed take a picture that shows the size of the infestation. 

3) Take some notes – Date, Trail and approximate location, What weed you think it is, Size of infestation. 

4) E-mail your report to  with the notes in the body of the e-mail. Even if you don’t have a GPS enabled phone send in as much information as you can gather, we’ll research it. ​​


Ten Noxious Weeds

Some facts about noxious weeds

• In Montana, spotted knapweed has decimated three million acres of elk habitat, contributing to a severe decline of 50-90% in the elk population. 

• In North Dakota’s Theodore Roosevelt National Park, leafy spurge has contributed to severe declines in bison (83%) and deer (70%) populations. 

• Throughout the West, eight million acres have been negatively impacted by the Star thistle. 

• According to the US Department of Agriculture, eleven western states have lost a total of ten million acres, covering national, state, and private lands. 

• In Colorado, 500 of our three thousand native species (seventeen percent) have been replaced by invasive weeds. 

• Within the past five generations, over 1 million acres in Colorado have become infested by invasive weeds, with an associated cost of over $10 million annually in lost productivity alone. 

• Since Russian knapweed was first reported in 1922, it has spread to infest over 160,000 acres. Similarly, since first reported in Colorado in 1962, Diffuse knapweed has spread to infest over 90,000 acres. 

• Leafy spurge, which was first reported in the State in 1970, currently infests about 85,000 acres. Infestations of invasive weeds not only have a substantial economic impact on farming and grazing, but they also have negative effects on native plant and wildlife species in natural areas and National Forests and Parks. 

• Tamarisk infestations along the Colorado River have virtually eliminated the native cottonwood riparian ecosystem in some places and have reduced nesting habitat for native songbirds by up to 41% in some areas. 

• Hoary cress infestations near Craig have reduced winter forage for elk and mule deer. 

• Purple loosestrife in the Colorado, South Platte, and ESWA watersheds has negatively impacted wetland species such as ducks, cranes, turtles, and fish. 

• Noxious weeds have displaced at least 10% of Colorado’s native plant species and severely degraded important native plant communities that are essential habitat for more than 85% of Colorado’s wildlife species.

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