Sierra Club Opposes Sonoma County Cannabis FEIR
November 7, 2025
Nov 7th Letter from the Sierra Club to the Sonoma County Board of Supervisors Opposing the Cannabis Program Update and Final Environmental Impact Report
SONOMA GROUP OF THE
REDWOOD CHAPTER
P.O. Box 466
Santa Rosa, CA 95402
sierraclub.org/redwood/sonoma
November 7, 2025
Via Electronic Mail
Members of the Board of Supervisors
County of Sonoma
575 Administration Drive, Room 100A
Santa Rosa, CA 95403
E-Mail: bos@sonomacounty.gov
Re: Sonoma County Comprehensive Cannabis Ordinance Program Update and Final Environmental Impact Report
Dear Board of Supervisors,
Sierra Club is concerned that the County of Sonoma’s Final Environmental Impact Report (FEIR) on the Cannabis Ordinance Program Update has failed to meet the legal requirements of the California Environmental Quality Act. In particular, the county has failed to fully address and mitigate the negative environmental impacts from outdoor cannabis grows that are clearly defined by the California Department of Fish and Wildlife (CDFW) in its July 15, 2025 comment letter on the Draft Environmental Impact Report.
Sierra Club urges the Board of Supervisors to delay final certification of the cannabis FEIR and direct staff to make revisions necessary to prevent, avoid and mitigate the negative environmental impacts identified by CDFW. We also urge you to direct staff to respond adequately to the comments from community groups and Shute Mihaly and Weinberger before finalizing the ordinance and FEIR.
The Sierra Club Sonoma Group of the Redwood Chapter includes thousands of members who live in Sonoma County. The Sierra Club is a grassroots, volunteer-led organization.
The Sierra Club does not have a formal policy on the legality of cannabis itself, but it is actively engaged in addressing the environmental impacts of cannabis cultivation and advocates for sustainable practices within the legal industry.
The Sierra Club supports strong environmental regulations for the legal cannabis industry. It has engaged in legal action, partnering with other local groups and Native American tribes in Yolo County to hold counties accountable for complying with environmental laws by evaluating and mitigating the full impacts of cannabis cultivation before adopting land use ordinances.
The Sierra Club Sonoma Group has strong concerns regarding Sonoma County’s cannabis ordinance and FEIR including the environmental issues listed below. We urge consideration of revisions that will eliminate or reduce negative environmental impacts, in particular those that were detailed the CDFW Draft EIR comment letter of July 15, 2025 but not adequately addressed or mitigated in the FEIR:
Crop Swaps
Ministerial permits for crop swaps are inappropriate. The crop swap ministerial alternative in the FEIR does not meet the requirements of CEQA and should be eliminated from the proposed ordinance.Among CDFW’s cited impacts are (pp. 3-4):
- The timing and quantity of water demand (based on semi-annual basis May 1 – October 31) for no net increase metric provides insufficient protection; a monthly metric is required.
- The infrastructure of cannabis is more intense than other crops, causing habitat fragmentation that threatens biodiversity.
- Imported soil for geo pots may be a vector for pathogens.
- New lighting may disrupt native wildlife; and
- Biotic Resource Assessments are required for each project.
CDFW recommends (p. 4), among other things, that the ordinance forbid ministerial crop swaps from using geo pots, imported soils, hoophouses, or new lighting. Water use must be net-zero seasonally using a monthly or finer resolution timescale. CDFW also recommends (p. 6) that Biotic Resource Assessment requirements be expanded to impacts to special-status species habitat that could occur and not be limited to federally-designated critical habitat.
Groundwater
Enhanced protection is needed for groundwater.
CDFW notes that the proposed ordinance EIR fails to recognize that “streamflow depletion due to groundwater pumping is well documented, and even modest pumping rates can reduce baseflow, especially in unconfined or shallow alluvial aquifers near streams.” Groundwater pumping is particularly problematic in “watersheds that support endangered and threatened aquatic species.”
CDFW recommendations regarding groundwater use are found on (pp. 7-8) and were not adequately addressed or mitigated in the FEIR.
Sierra Club believes that allowing cannabis cultivation in over-drafted and ecologically sensitive watersheds will inevitably cause significant adverse impacts for which there are no sufficient mitigations. Such areas should be excluded from cannabis cultivation.
Trees
As stated by CDFW: The cannabis ordinance EIR identifies potential significant effects to sensitive plant communities, large trees (≥20-inch diameter at breast height [dbh]), and oak woodlands (Impact 3.4-4), and includes Mitigation Measures 3.4-4a and 3.4-4b. However, it does not establish specific significance thresholds for cumulative oak woodland loss or mature tree removal, which may allow biologically important conversions to occur incrementally under ministerial permits. It also relies heavily on tree replacement or on-site mitigation but does not sufficiently evaluate whether replacement is feasible or ecologically equivalent. Lastly, it does not provide clear mechanisms to assess cumulative loss of oak woodland or old-growth trees.
The following CDFW recommendations were not adequately addressed or mitigated in the FEIR:
- Establish significance thresholds for tree and woodland conversion. For example, projects resulting in oak woodland loss should be considered potentially significant and ineligible for ministerial approval.
- Establish cumulative impact tracking across ministerial permits, such as the County maintaining a GIS-based system to monitor oak woodland removal and canopy loss regionally.
- Prohibit removal of mature or legacy trees (e.g., >36-inch dbh, or estimated >100 years old).
- Require off-site mitigation for all tree removal exceeding on-site replanting capacity, with a preference for conservation easements, native habitat restoration, or purchase of appropriate credits from an approved mitigation bank.
Tiger Salamander
CDFW points out that the EIR does not include protective measures to mitigate all potentially significant impacts on CTS where:
CTS occurrences are documented in areas outside the formally designated Santa Rosa Plain, such as parts of rural Petaluma, Penngrove, Cotati, and southwest Sonoma County.Impacts to upland and dispersal habitat are allowed under the ministerial pathway (crop swap).
CDFW makes the following recommendations (pp. 10-11) that were not adequately addressed or mitigated in the FEIR:
- Expand exclusion zones for ministerial permitting to include areas within 1.3 miles of all known CTS occurrences, including outside the formal Santa Rosa Plain boundary (e.g., rural areas of Southwest Petaluma,
- USFWS critical habitat mapping, and local surveys should be used to inform this expanded buffer.
- Require full CEQA review under the County’s Use Permit process for any cultivation project proposed in areas with suitable CTS habitat, regardless of zoning or CH status. Site-specific assessments should consider upland burrow habitat, not just aquatic features.
- Require ITPs from CDFW for any project with potential to impact CTS through direct take such as through habitat alteration, or barrier creation. The County should not approve ministerial permits in such cases.
- Restrict the use of rodenticides, herbicides, and synthetic pesticides in areas with suitable CTS habitat, and prohibit the use of rodenticide-laced grain in ground squirrel and gopher burrows.
Biotic Resource Assessments Need Performance Standards.
CDFW recommends (p. 11) that biotic resource assessments have performance standards and survey protocols to ensure rigor in biological impact evaluations. Enforceable standards are needed for field survey timing and methodology, otherwise special-status species or sensitive habitats will be undetected, especially cryptic or seasonally detectable species. The presence of such species can be missed by a one-time survey, especially if conducted outside of the correct time window.
Riparian/Wetlands Setbacks
CDFW notes (p. 13) that site-specific cannabis activities can be variable, and “one size fits all” setbacks may be insufficient to avoid adverse effects on special-status species. For this reason, CDFW recommends (p. 14) the County evaluate each cultivation site individually and reserve the right to require greater setbacks as needed. CDFW then specifies six specific changes in the proposed ordinance to implement this recommendation.
Thank you for taking the time needed to revise the Cannabis ordinance FEIR to respond fully to the environmental impacts as identified by CDFW; Shute Mihaly and Weinberger, the Neighborhood Coalition and other commenters to ensure compliance with CEQA.Sincerely yours,
Sonoma Group Sierra Club Executive Committee
Shirley Johnson, Chair, Dan Mayhew and Teri Shore
david.rabbitt@sonomacounty.gov