County of Monterey
Emergency, Readiness, Response, and Recovery

Current Emergency Information

Soil

Community Soil Sampling Results

Revised Phase 1 Soil Sampling Report Posted – No Changes to Findings

A Revised Phase 1 Community Soil Sampling Report related to the Moss Landing battery facility fire is now available. The revised report responds to comments from California Department of Toxic Substance Control (DTSC), the California Department of Public Health (CDPH), and the Regional Water Quality Control Board (RWQCB), but does not include new data and does not change any conclusions from the original August 22, 2025, report.

The Community Soil Sampling Plan at Moss Landing was designed to gather critical data for a human health risk assessment, helping determine whether additional sampling, actions, or mitigation measures are needed. Sampling was conducted by Terraphase Engineering under the oversight of the Monterey County Health Department Environmental Health Bureau (EHB) and the California Department of Toxic Substances Control (DTSC), with review and input from other state and regional partners.

Why the Report Was Revised

The October 17, 2025 revision updates text, clarifies methodology, and includes agency-requested explanations. The underlying sampling data and interpretation remain unchanged.

Will There Be Additional Revisions to the Phase 1 Report?

No further revisions are expected.

DTSC has reviewed the revised report and has no additional comments.
CDPH provided a follow-up memo (attached on the County website) with additional recommendations and technical discussion of background values and particulate behavior.
Rather than engage in extended back-and-forth revisions to the Phase 1 document, the County has directed Vistra’s consultant to address CDPH’s comments within the upcoming Preliminary Environmental Assessment (PEA), where they can be evaluated in the broader multi-media context (soil, sediment, water, and air).

A full analysis of both health and environmental data, including whether more site investigation is needed, will be provided in the PEA report

What’s Next

The Phase 2 Sediment, Surface Water and Porewater Sampling Report is expected to be released in January 2025. Data from the Phase 1 and 2 sampling will be integrated into the Preliminary Environmental Assessment (PEA), anticipated for release in March 2026 following state agency review.

---------------------------------------------------------

Original Report Posted September 22, 2025

Soil sampling took place between May 8 and June 20, 2025, at 27 locations in Moss Landing and surrounding North Monterey County, resulting in 108 individual samples. Analyses included metals associated with battery fires (aluminum, copper, cobalt, lead, lithium, manganese, nickel) as well as combustion byproducts (PAHs, dioxins, and furans).

Phase 1 Community Soil Sampling Report_Terraphase_082225

Agency Coordination and Comment

The Soil Sampling Report was reviewed by state and regional partners, including:

DTSC-HERO (Human and Ecological Risk Office)
CDPH-EHIB (California Department of Public Health – Environmental Health Investigations Branch)
Regional Water Quality Control Board, Central Coast Region

To ensure completeness and accuracy, EHB transmitted the following agency comment packages to Vistra and Terraphase:

Key Findings

No widespread contamination observed. No detections of aluminum, copper, lithium, nickel, PAHs, or dioxins/furans above health-related screening criteria.
Localized exceedances observed. Cobalt, lead, and/or manganese exceeded screening levels in 8 of 108 samples.
A County-prepared summary of the Terraphase Soil Sampling Report is available here.

Next Steps

The County and partner agencies remain committed to a thorough, science-based review process. While early results are generally reassuring, additional evaluations are underway to ensure the long-term health of the community and environment.

Soil Sampling Plan Development

Archive

Soil Testing Results from Elkhorn Slough Reserve

The California Department of Fish and Wildlife (CDFW) conducted two rounds of soil sampling at the Elkhorn Slough Reserve in response to the January 2025 Moss Landing battery fire. The first round of samples was collected on April 09, 2025, from areas most frequently used by staff. A second round was completed on April 30, 2025, which included additional testing locations. The soil was tested for metals commonly associated with lithium-ion batteries, including cobalt, copper, lithium, manganese, and nickel.

Laboratory results from both rounds of sampling showed that all measured concentrations were below worker exposure thresholds set by the California Department of Toxic Substances Control (DTSC) and the U.S. Environmental Protection Agency (US EPA). These results suggest there is no elevated health risk to workers or visitors at the Reserve in the areas tested.

The full reports are available below, and the data will also be added to the Moss Landing Vistra Battery Fire Data Viewer to keep the community informed.

California Department of Toxic Substances Control (DTSC)

In response to the battery fire incident, soil sampling was promptly initiated to determine the extent of potential contamination in areas directly and indirectly impacted by the soot deposition plume and smoke. The California Department of Toxic Substances Control (DTSC) collected soil samples at 7 locations in the community surrounding the incident site, focusing on residential and public spaces likely to have been exposed to airborne particulates. Santa Cruz County gathered samples of agricultural soil and sediment from the southern portion of the neighboring county to assess potential impacts to food production areas and natural environments. These soil samples were analyzed in an approved laboratory to identify and quantify contaminants, providing essential data for evaluating long-term human health risks. Soil analysis is a key component of the broader environmental health investigation, as it supports decision-making around remediation and long-term land use.

DTSC Moss Landing Sampling Report February 24, 2025
- Attachment 1 - Overview Sample Map

Screening Level Human Health Risk Assessment for a Residential Exposure Scenario Based on Data from the Moss Landing Battery Fire: An Analysis of the Department of Toxic Substances Control (DTSC) Soil and Surface Water Data Including supporting documents February 18, 2025

Santa Cruz Agricultural Soil Sampling

Santa Cruz County has conducted environmental testing through the Santa Cruz County Agricultural Commissioner and the County’s Environmental Health Division, following established industry protocols. The testing focused on areas in South County most likely to be impacted by the recent fire and included analysis of soil, plant material, surface water, and sediment.

Agricultural soil samples were collected at both surface and subsurface levels to allow for comparative analysis. Surface water and sediment samples were collected from several locations, including Drew Lake, Kelly Lake, Pinto Lake, and the Watsonville Slough. Additional samples were taken from Antonelli Pond, Loch Lomond Reservoir, and Forest Lake, which served as spatial controls due to the absence of pre-existing background data.

In addition, the California Department of Public Health (CDPH) reviewed the soil sampling results collected from agricultural fields. In a memo dated February 25, 2025, CDPH confirmed that none of the metal concentrations in the samples exceeded health-based soil screening values. These values are designed to protect sensitive populations. Based on this analysis, CDPH concluded that the metal concentrations found in the agricultural soil samples do not pose a health risk to the public.

CDPH Assessment of Santa Cruz County Ag Soil Sampling

Environmental Health – Surface Water Results

County of Santa Cruz Ag Commission: Soil

County of Santa Cruz Ag Commissioner: Plant Tissue

County of Santa Cruz Environmental Health: Sediment

The County of Santa Cruz issued a news release on February 21, 2025, summarizing the results:

Evaluation of Heavy Metals in Agricultural Fields following the Moss Landing Battery Fire

On March 19, 2025, the Division of Agriculture and Natural Resources released the results of a limited study on the presence of heavy metals in soil collected from agricultural fields near the battery fire site, considering both potential contamination and native concentrations. The County of Monterey has requested the laboratory reports associated with the study to facilitate review and interpretation by state partners.

The study was conducted by farm advisors from the University of California who serve Monterey, Santa Cruz, and San Benito counties. The County of Monterey Agricultural Commissioner confirms that these advisors have decades of experience and expertise in vegetable crop production systems, natural resources management, soil science, water quality, and plant nutrition. Across California, more than 300 farm advisors provide impartial, science-based research and communication to support agricultural, economic, and natural resource decision-making.

The County of Monterey does not take a position on the findings of this limited study but remains committed to supporting a thorough scientific review by the appropriate state agencies.