Herbicide spraying on Boulder County public lands to start again.

At a meeting on May 21, 2026, county commissioners Claire Levy (clevy@bouldercounty.gov) and Marta Loachamin (mloachamin@bouldercounty.gov) voted to recommence spraying indaziflam on our public lands via drone. The spraying is scheduled to begin again on November 1st.

In December, 2025, Boulder County announced that they were going to spray herbicides on cheatgrass on open space above five regenerative and organic farms (on Red Hill near Lyons). So a coalition of environmental groups got to work, calling on our members to contact county officials and voice their opposition to the spraying. Over 1,000 people contacted the county commissioners and it worked: at their February 26 public hearing on herbicides, the county commissioners paused the herbicide spraying until fall 2026. But at the meeting on May 21st, Commissioners Levy and Loachamin voted to start the spraying again. So our fight against the spraying starts again as well.

County Commissioner Ashley Stolzmann has been firmly against herbicide use for her entire tenure as commissioner, and we thank her for her ethical leadership on this issue.

We need to persuade public officials that we do not want poisons used on our public lands. We need to continue working on outreach, helping the public understand how dangerous herbicides are to human and ecological health.

Background: For many years now, Boulder County open space staff have been using the herbicide indaziflam on hundreds of acres of county public lands. Once applied, these toxic chemicals will remain in the soil for 2-9 years. As a pre-emergent herbicide, indaziflam prevents seeds from sprouting, whether they are annual or perennial seeds, non-native or native, “weed” or cultivated plant. In short, the soil becomes non-productive and can stay that way season after season.

Indaziflam can also have toxic effects on humans, other mammals, pollinators, and aquatic creatures of all forms. No matter how carefully applied, it can leach into groundwater, streams, and ponds; drift is also a problem.

Recently, Public Employees for Environmental Responsibility (PEER) released a report saying that toxic “forever chemicals”—PFAS—have been found in indaziflam (read article here). 

The state of Colorado is phasing out the use of PFAS, so it is time to phase out indaziflam.

Contact information for the Boulder County Commissioners:

Marta Loachamin: mloachamin@bouldercounty.gov

Ashley Stolzmann: astolzmann@bouldercounty.gov

Claire Levy: clevy@bouldercounty.gov

Educate yourself on this issue—go here for more information:  https://www.pesticidesbouldercounty.org/indaziflam.

Background:

On February 3, 2026, Marta Loachamin and Ashley Stolzmann voted to pause the spraying of herbicides on Red Hill. This victory from more than a thousand Boulder County residents contacting our county commissioners, asking them to stop the spraying. Scores of residents have shown up at meetings as well--as happened at the county commissioner town hall on January 22, where over 20 people stood and asked the commissioners to stop the spray. 

What indaziflam does: As a pre-emergent herbicide, indaziflam prevents seeds from sprouting, whether they are annual or perennial seeds, non-native or native, “weed” or cultivated plant. In short, the soil becomes non-productive and can stay that way for 2-7 years, preventing all seeds from sprouting.

Indaziflam can also have toxic effects on humans, other mammals, pollinators, and aquatic creatures of all forms. No matter how carefully applied, it can leach into groundwater, streams, and ponds; drift is also a problem.

Indaziflam has been found to contain PFAS, forever chemicals. Read more here.

Contact information for the County Commissioners:

Marta Loachamin: mloachamin@bouldercounty.gov

Ashley Stolzmann: astolzmann@bouldercounty.gov

Claire Levy: clevy@bouldercounty.gov

Educate yourself on this issue—go here for more information:  https://www.pesticidesbouldercounty.org/indaziflam.

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Political Committee

Who We Are:

The mission of the Sierra Club political program is to preserve the environment through nonpartisan grassroots political action. These are principal goals of the program:

•     To elect candidates who will support and promote environmental protection
•     To raise public awareness about environmental issues and elevate the priority of these issues for decision-makers
•     To encourage Club members and other environmentalists to participate in the political process
•     To advance the Club's conservation agenda by building relationships with legislators and other elected officials
•     To strengthen the Sierra Club's capacity to elect pro-environment candidates at every level of government