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Project: Advisory Panel for CECs in Recycled Water

Background and Objectives

Constituents/chemicals of emerging concern (CECs) represent a challenging problem for regulators to address, owing to limited scientific knowledge about their sources, fates, and effects. The California State Water Resources Control Board (SWRCB) issued a Recycled Water Policy in 2009 that, among other efforts, sought to incorporate the most current scientific knowledge on CECs into regulatory policies for use by various state agencies. SCCWRP facilitated a panel of six experts to provide recommendations to the SWRCB. This "blue ribbon" panel was asked to address the following questions:

1. What are the appropriate constituents to be monitored in recycled water, and what are the applicable monitoring methods and detection limits?

2. What toxicological information is available for these constituents?

3. Would the constituent list change based on level of treatment? If so, how?

4. What are the possible indicators (i.e. surrogates) that represent a suite of CECs?

5. What levels of CECs should trigger enhanced monitoring in recycled, ground or surface waters?

The panel deliberated over a series of meetings and published its recommendations in 2010. These recommendations served as the basis for CEC monitoring requirements adopted by the SWRCB in the Policy amended in 2013. A second, related panel was later formed to address CECs in coastal and marine ecosystems.


The original Panel recommendations were submitted in 2010. The Panel was reconvened in 2017 to incorporate the latest science and update the original recommendations for an expanded scope of recycled water applications. The expanded scope includes the following:

6. Consider what additional monitoring for CECs, if any, is needed for recycled water used for surface water augmentation.

7. Evaluate the potential human health risks associated with the use of recycled water for all uses allowed under Title 22 (e.g. crop irrigation), excluding ingestion of food crops as a route of exposure.

8. Provide research recommendations for antibiotic- resistant bacteria and antibiotic resistance genes related to human health potentially impacted by recycled water applications allowed under Title 22 and for surface water augmentation.

The updated report is scheduled for completion in 2018.


Six original Panel members were chosen for their expertise in the following fields: biochemistry, analytical chemistry, civil engineering, epidemiology/risk assessment, ecotoxicology, and human health toxicology. This Panel reviewed the scientific literature regarding CECs in recycled water, and met periodically to discuss how to answer the key questions. Following the release of a draft report in spring 2010, the Panel collected comments from stakeholders, including public interest groups and environmental organizations, and refined its recommendations. A final report was issued to the SWRCB for consideration in summer 2010. Prior to adoption, findings and recommended actions were considered by SWRCB staff with input from the public and the California Department of Public Health. For the project update initiated in 2017, a seventh Panel member with expertise in antibiotic-resistant bacteria was added to the Panel. The Panel was instructed to follow the same process developed in 2010.

Calendar (2017-18)

Event Related Materials
Jun. 4
Panel re-convened
Jul. 19-21 Panel Meeting #1


 Oct. 24
Release of SWRCB schedule for amending CEC monitoring recommendations for recycled water
Dec. 11-15 Panel Meeting #2

Final Agenda


Video Recording

Jan. 31 Draft Report for Review Monitoring Strategies for Constituents of Emerging Concern in Recycled Water: Recommendations of a Science Advisory Panel (Draft Final Report)
March 2

Public Comments on Draft Due

April 25

Final Report due to SWRCB
Monitoring Strategies for Constituents of Emerging Concern in Recycled Water: Recommendations of a Science Advisory Panel (Final Panel Report)
June 11

Bioanalytical Screening Workshop


Video Recordings (Two viewing options)
Dec. 31

Project end date


In 2010, the Panel produced several products to guide the state’s recycled water management approaches. First, the Panel developed a framework for prioritizing and selecting CECs for recycled water monitoring programs. This framework was then applied to recommend a short list of monitoring parameters, including both health-based indicators (i.e., toxicologically relevant CECs) and performance-based indicators (i.e., CECs with representative physicochemical properties and structures tested to demonstrate a capacity for removal by a particular water treatment process). The list also incorporates CECs from multiple source classes (e.g., pharmaceuticals, personal care products, food additives, hormones). Four health-based and five performance-based indicators were identified for recycled water used for groundwater recharge, while only three surrogate parameters were recommended for monitoring water used for landscape irrigation (turbidity, chlorine residual, and total coliform bacteria). The Panel additionally developed guidance for interpreting and responding to monitoring results.

Lastly, the Panel recommended several key areas for future efforts. To overcome the limitations associated with measuring individual chemicals, the Panel recommended use of bioanalytical screening tools, which use molecular and genetic techniques to test for different classes of toxicological effects. Other recommended future activities included (a) improving the recycled water CEC database through a comprehensive review of literature and occurrence studies outside California, and (b) providing programmatic support for data management, application of the selection framework, and periodic review of the original monitoring recommendations.


This project is being conducted in collaboration with the State Water Resources Control Board, a group of stakeholder advisors, and the seven Panel experts (below).

Panel members:

  • Dr. Paul Anderson - Human Health Toxicologist
  • Dr. Nancy Denslow - Biochemist
  • Dr. Jörg Drewes - Civil Engineer
  • Dr. Adam Olivieri - Epidemiologist/Risk Assessor
  • Dr. Daniel Schlenk - Environmental Toxicologist
  • Dr. Shane Snyder - Analytical Chemist
  • Mr. Walt Jakubowski - Microbiologist

Click here to view the biographies of all seven Panel experts.

Stakeholder Advisors:

  • Sean Bothwell (California Coastkeeper Alliance)
  • Ann Heil (Sanitation Districts of Los Angeles County)
  • Bobbi Larson (California Association of Sanitation Agencies)
  • Mark Millan (Town of Windsor)
  • Jeff Mosher (Water Environment and Reuse Foundation)
  • Megan Plumlee (Orange County Water District)
  • Toby Roy (San Diego County Water Authority)
  • Jennifer West (WateReuse California)
  • Debbie Webster (Central Valley Clean Water Association)
For more information on the Recycled Water Advisory Panel and to be added to a listserve to automatically receive project updates, contact Keith Maruya at (714) 755-3214.
This page was last updated on: 6/13/2018