New Study to Support Water Quality Protection in the Smith River Plain

SACRAMENTO – The California Department of Pesticide Regulation (DPR) is announcing a new, multi‑year scientific study to better understand how copper concentrations in tributaries of the Smith River Plain may be affecting local fish species and the broader aquatic ecosystem. The study will provide new data to support the North Coast Regional Water Quality Control Board’s (North Coast Water Board’s) ongoing oversight and water quality protection efforts in the Smith River watershed.

Beginning this year, DPR will fund a two-year toxicity study led by researchers at Cal Poly Humboldt, using field collected water and laboratory testing to assess potential effects on fish health and behavior, and on sensitive invertebrate species.

This study responds to questions raised by community members, Tribal representatives, and other interested groups about pesticide runoff in the Smith River Plain, where copper fungicides are widely used in lily bulb production. The work will generate additional data needed to better understand copper bioavailability, or how much copper organisms can absorb and how quickly it may have an effect.

The results of this study will support the North Coast Water Board’s ongoing water quality protection efforts in the Smith River Plain, including development and implementation of waste discharge requirements for lily bulb farming operations (a.k.a. Lily Bulb Order). The study represents a collaboration between the Water Boards and DPR on continued work across both departments to protect the environment and engage with local communities and Tribes.

The study will initiate in 2026 and is anticipated to conclude in 2028.

More information on the Smith River Watershed is available on the North Coast Water Board’s website.

Contacts

DPR:
Amy MacPherson, Deputy Director of Outreach & Communications
(916) 445-4315 | Amy.MacPherson@cdpr.ca.gov

State Water Resources Control Board:
Blair Robertson, Public Information Officer
(916) 341-5263 | Blair.Robertson@Waterboards.ca.gov