5 Bay Area Groups Urge Herbicide Moratorium After Imazapyr Tree Loss

Five Bay Area environmental and civic organizations are calling on the Mountain View City Council to enact an immediate moratorium on routine herbicide use in public parks, street tree wells, and landscaped medians after 5 years of municipal applications of the weed killer imazapyr left more than 30 public shade trees removed and approximately 150 additional trees deteriorating, according to a Guest Opinion by GreenSpacesMV leaders Tracy Ferea and Rashmi Sahai and Santa Clara Valley Bird Alliance environmental advocate Shani Kleinhaus in the Mountain View Voice.

Five Years of Imazapyr Applications and Sept. 27 Coalition Letter

According to the authors, Mountain View city staff approved the use of imazapyr in 2021 and applied the herbicide for the past 5 years to control weeds around public trees — including large shade trees lining Franklin Street in front of the Mountain View Public Library that were cut down in July 2026 due to declining health. Chemical testing detected imazapyr in every soil and tree-tissue sample examined.

While the city has halted the use of imazapyr, begun treating contaminated soil, and pledged to replace removed trees with native species, staff have not committed to pausing herbicide use overall, instead reviewing alternative weed-control products to reduce or eliminate pesticide use "as feasible."

On Sept. 27, 5 organizations — GreenSpacesMV, the Santa Clara Valley Bird Alliance, the Mountain View Coalition for Sustainable Planning, Livable Mountain View, and the Sierra Club Loma Prieta Chapter — sent a joint letter urging the City Council to adopt an immediate herbicide moratorium across all publicly maintained landscaped areas until the city overhauls its policies. A staff response sent on behalf of the council stated only that the city would "review and consider" the request without setting a timeline.

2002 Integrated Pest Management Policy and Regional Precedents

The coalition noted that Mountain View's own Integrated Pest Management policy, adopted in 2002, requires reducing or eliminating chemical pesticides wherever feasible and practical, and questioned why staff approved imazapyr in 2021 despite U.S. Environmental Protection Agency warnings issued in 2006, more than 300 tree losses in Milwaukee County in 2017, and 2024 reports of hundreds of harmed trees in Ventura County.

Pointing to neighboring Peninsula cities — where Palo Alto has not used pesticides on public trees since 2012 and the Menlo Park City Council voted in 2017 to eliminate herbicides from all city parks — the 5 groups urged Mountain View to rely on mulch and manual weed removal, release pesticide application records online, and report regularly to the Parks and Recreation Commission.