Central Valley TMDL Projects
Pyrethroid Pesticides TMDL
and Basin Plan Amendment

To request a copy of documents listed on this page, please contact Jessica Rader at Jessica.Rader@waterboards.ca.gov or (916) 464-3199.

On 8 June 2017, the Central Valley Water Board adopted Resolution R5-2017-0057, which adopted the Basin Plan Amendment (BPA) for the Control of Pyrethroid Pesticide Discharges and approved the supporting Substitute Environmental Documentation and Staff Report.

This BPA established measurable pyrethroid concentration goals and a program of implementation for the control of pyrethroid pesticides that are impacting or could potentially impact aquatic life uses in surface waters in the Sacramento and San Joaquin River watersheds of the Central Valley. It also established Total Maximum Daily Loads (TMDL) for waterbodies that are listed as impaired by pyrethroids on the Clean Water Act Section 303(d) list, and established provisions to address and/or prevent future pyrethroid listings.

The BPA was approved by the State Water Resources Control Board on 10 July 2018 and was approved by the Office of Administrative Law (OAL) on 19 February 2019. With OAL approval, the BPA (apart from TMDLs) became fully approved and effective. On 22 April 2019, the United States Environmental Protection Agency (USEPA) approved the Pyrethroid TMDLs included in this BPA for nine urban creeks in Sacramento and Roseville. With USEPA approval, the BPA and TMDLs are now fully approved and effective.

Adoption and Approval Materials

  • United States Environmental Protection Agency Action
    • USEPA Approval Letter - 22 April 2019
    • TMDL Checklist
  • Office of Administrative Law Action
    • OAL's Notice of Approval, Endorsed Form 400, and Concise Summary (OAL File No. 2019-0107-03S)
  • State Water Board Action
    • Final State Board Resolution (2018-0031)
    • State Water Board Meeting - 10 July 2018
      (Includes Agenda, Draft Resolution, Final Staff Report, Written Comments, and Response to Comments)
    • Notice of Opportunity to Comment, 3 October 2017
  • Central Valley Regional Water Quality Control Board Action
    • Pyrethroids Method Development (Analytical Test Method Request and Laboratory Participation Questionnaire can be found under "Informal Workgroups")
    • Resolution R5-2017-0057 (includes final adopted Basin Plan Amendment language) - Adopted 8 June 2017
    • Final Staff Report (including CEQA Environmental Checklist and environmental analysis) - June 2017
    • Final Response to Comments
    • Agenda Package (including comments, summary sheet, resolution)
    • Late Revisions
    • Final Response to Peer Review Comments
    • Notice of Public Hearing

NEW - Draft Pyrethroid Research Plan

Notice of Staff Workshop (Español) for the Draft Pyrethroid Research Plan – 12 March 2024

During the development of Resolution R5-2017-0057, Regional Board staff recognized that the data used to evaluate the potential for registered pyrethroid products to cause or contribute to water quality concerns contained considerable knowledge gaps. Therefore, Resolution R5-2017-0057 was drafted to include a provision that the Regional Board will work with stakeholders to develop a Pyrethroid Research Plan that will describe research and other special studies to inform future iterations of this control program (e.g., potential objectives, program refinement).

In 2022, Regional Board staff performed a literature review to identify any additional knowledge gaps and/or studies that may be useful to fill the initial knowledge gaps identified in Resolution R5-2017-0057. In addition to the identification of scientific knowledge gaps, Regional Board staff identified management questions that will inform pyrethroid and other replacement pesticide regulations.

The Regional Board aims to use pyrethroid research to inform science-based pyrethroid management in the Sacramento and San Joaquin River Basins, thereby protecting beneficial uses. The Draft Pyrethroid Research Plan does not contain any new regulations or requirements. Rather, staff intend the Pyrethroid Research Plan to serve as a basis upon which the science community may develop research proposals that will aid in addressing the Regional Board management questions.

For project updates, please subscribe to the TMDL – Central Valley Pyrethroids email list available on the upper right corner of this page.

NEW - Pyrethroid Analytical Methods Validated for Compliance Monitoring

The Central Valley Water Board issued a request on 13 March 2019 that Environmental Laboratory Accreditation Program (ELAP) accredited laboratories develop performance-based analytical methods that can achieve the lower concentration goals required to assess compliance with the Pyrethroid BPA and TMDL. This is because the BPA sets low concentration goals for pyrethroids in discharge and receiving water, and therefore lower analytical reporting limits than commonly commercially available will be required for compliance monitoring.

The Central Valley Water Board has reviewed validation packages submitted in response to this request. As of 6 May 2020, the laboratories listed below have analytical methods that have been approved by the Central Valley Water Board for use in assessing compliance with the BPA. The appropriate contacts for each laboratory are included. This list will continue to be updated as additional laboratories have methods validated and approved by the Central Valley Water Board in the future.

Lab Name Point(s) of Contact
Physis Environmental Labs
1904 E. Wright Circle
Anaheim, CA 92806
Rich Gossett
Technical Director
Office: (714) 602-5320 ext. 201
Cell: (310) 420-4964
Caltest Analytical Laboratory
1885 North Kelly Rd.
Napa, CA 94558
Shawna Rees
Laboratory Director
(707) 258-4000

Information for quotes may be sent to:
McCampbell Analytical, Inc.
1534 Willow Pass Rd
Pittsburg, CA 94565
Theresa Johnson
Director QAQC

Kevin Bowen
Pyrethroid Chemist

Griselda Martinez
Technical Supervisor

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