Petaluma River Bacteria TMDL


Petaluma River is listed on the Clean Water Act 303(d) list of impaired water bodies due to elevated fecal indicator bacteria levels (e.g., E. coli). High fecal indicator bacteria levels indicate presence of pathogenic organisms that are found in warm-blooded animal (e.g., human, cows, horses, dogs, etc.) waste and pose potential health risks to people who recreate in contaminated waters. Petaluma River is also listed as impaired due to excessive algae growth, known as eutrophication, which is caused by high nutrient (nitrogen and phosphorus) levels. Eutrophic waters can significantly alter dissolved oxygen and pH levels, which are critical to aquatic wildlife and can impact recreational beneficial uses.

The Petaluma River Bacteria and Nutrients TMDL was initiated to address the current impairment of aquatic wildlife and recreational beneficial uses in this water body. Potential anthropogenic nutrients and bacteria sources in the watershed include livestock, municipal stormwater runoff, septic systems, sanitary sewer systems, pet waste, and vessel marinas. We conducted an impairment analysis for nutrients and pathogens as documented in the project report below. Nutrient concentrations and algae biomass were not consistently elevated in the Petaluma River and tributaries, therefore, we do not have data to warrant a nutrient TMDL at this time. However, fecal indicator bacteria exceeded the applicable water quality standards in Petaluma River and tributaries. Consequently, we initiated the process of developing a bacteria TMDL to identify sources of fecal contamination, and specify actions to reduce bacteria to levels that will support recreational beneficial uses.

 Photo of a meandering Petaluma River in the lower watershedPhoto of people boating near a marina on the Petaluma River

New September 2023 – Notification Letter for Onsite Wastewater Treatment System (Septic System) Owners

The Regional Water Board staff recently mailed out a notification letter to the property owners who own septic systems, which are partially or fully located within 200 feet of the Petaluma River or its major tributaries, to provide certain basic information about their systems to the Regional Water Board. Septic systems are an identified source of fecal pollution in the Petaluma River watershed. The purpose of the letter is for the identified property owners to initially provide some basic information about their septic system so that we can better categorize and focus on addressing those systems with the highest threat to water quality.

An interactive map of the identified parcels, to help property owners verify we have correctly identified them, is available below.

Parcel Map – Identified parcels with septic systems within a 200 feet boundary of the Petaluma River or its major tributaries

U.S. Environmental Protection Agency Approval

The U.S. Environmental Protection Agency approved the TMDL on May 10, 2021. The TMDL is now fully approved and effective. This final approval starts the timeline for all required actions.

Office of Administrative Law Approval

California Office Of Administrative Law (OAL) Approved the Regulatory Action on October 26, 2020

State Water Board Approval Process

The State Water Board adopted Resolution No. 2020-0018 approving the Basin Plan amendment to establish the Petaluma River Watershed Bacteria TMDL on June 2, 2020.

The State Water Resources Control Board (State Water Board) hearing to approve the TMDL Basin Plan amendment (BPA) is scheduled for June 2, 2020. The public comment period closed on April 13, 2020. Non-substantive revisions have been made to the BPA and Staff Report and these revisions are detailed in the Executive Officer’s Corrections Memorandum to the State Water Board.

State Water Board Meeting Agenda and associated documents are available below.

San Francisco Bay Regional Water Board Adoption Process

The Regional Water Board adopted a resolution approving the Basin Plan amendment for this TMDL on November 13, 2019. The final versions of the relevant documents associated with the Regional Water Board Adoption process are available below.

Final Regional Board Adopted Documents (November 13, 2019):

TMDL Development Process:

Project Timeline

  • Initial public meeting – June 2017
  • Release of draft documents for preliminary public review – spring 2018
  • Project workshop and CEQA scoping meeting– spring 2018
  • Release of final documents for formal public review – summer 2019
  • Close of public review period – September 3, 2019
  • San Francisco Bay Regional Water Board adoption hearing for the proposed Basin Plan amendment – November 13, 2019
  • State Water Board adoption hearing - June 2, 2020

Please Join Our Mailing List

The Water Board maintains an email notification list for our TMDLs called: “ALL Basin Planning/TMDL Notices and Information.” To ensure you receive future information on this TMDL, we encourage you to subscribe to this list. The instructions for subscribing to the list are provided on the subscriptions page, which you can reach by clicking here.

For more information contact:

Farhad Ghodrati
Environmental Scientist
San Francisco Bay Region
1515 Clay Street, Suite 1400
Oakland, CA 94612
Phone: 510-622-2331
Fax: 510-622-2460