Revisions to Bacteria TMDLs in the San Diego Region

Project Goal

To develop an updated plan to attain water quality standards in water bodies that have been identified as impaired for fecal contamination.

Project Objectives

  • To clarify and streamline TMDL goals.
  • To update numeric targets to be consistent with statewide bacteria water quality objectives.
  • To emphasize implementation actions that address human sources of fecal indicator bacteria.

Project Area

The project area includes portions of the following Hydrologic Units: San Juan, San Luis Rey, Carlsbad, San Dieguito, Los Peñasquitos, San Diego, and Pueblo San Diego. Tribal Reservations are shown on the map for informational purposes only. The San Diego Water Board does not regulate discharges on Tribal Reservations.

map of the project area


Tentative Schedule

Tentative Schedule Timeline

 

Staff Recommended Actions

  • Limit scope to existing TMDL waterbodies
  • Update numeric targets to be consistent with statewide bacteria objectives
  • Update Source Analysis to reflect findings of special studies
  • Update Implementation Plan to focus on sources of human fecal contamination
  • Allow for the use of human fecal source identifiers as a management tool
  • Evaluate compliance dates

Topics to Consider

  • Science continues to evolve with regards to alternative indicators for identifying fecal contamination
  • Climate change considerations can add greater complexity to TMDL analyses, including the need to assess future conditions that are themselves uncertain.
  • The Natural Source Exclusion and Reference System Approach will need to be evaluated to determine how to consider for source variability within urban environments.

Background

The contact water recreation (REC-1) project was first introduced during the 2015 Triennial Basin Plan Review. At the time, the focus of the project was to determine whether and to what extent data supported amending bacteria water quality objectives, implementation provisions for applicable bacteria TMDLs, or the TMDLs themselves. Bacteria TMDLs were adopted in June 2008 and February 2010.

In July 2018, San Diego Water Board staff prepared a summary report of the 2015 REC-1 Triennial Review Project that made recommendations for next steps. Recommendations were based on discussions and feedback from external and internal workgroups as well as the various technical studies that had been completed. During the 2018 Triennial Review, the focus for the project shifted towards implementation of actions that were identified in the 2018 recommendations report. The short-term actions included updates to the existing storm water permit, audits of Illicit Discharge Detection and Elimination programs, updates to waste discharge requirements for sanitary sewer systems, and updates to Chapter 3 in the Basin Plan.

During the 2021 Triennial Review the focus shifted towards the development of a narrative risk-based objective that would be protective of the REC-1 beneficial use; this work also intended to include the development of a numeric translator for HF183 (a human specific bacteria indicator) to implement the narrative objective. Furthermore, the project indicated the Board would initiate revisions to the bacteria TMDLs. Updates to the bacteria TMDLs were pending results of various special studies in the region, such as the work required in the San Diego River Investigative Order R9-2019-0014. Order No. R9-2019-0014 was issued to local agencies to identify and quantify relative contributions of actual and suspected sources and transport pathways of human fecal material in dry and wet weather discharges to the Lower San Diego River Watershed. The final report for the San Diego River Investigative Order was submitted to the San Diego Water Board in June 2024; results of this, and other studies, will be used to inform updates to the TMDLs and implementation plan.

Additional Information and Links

  • My Water Quality: Swimming Safety
  • SSS Incident Map | California State Water Resources Control Board
  • Alternative Indicators of Human Fecal Contamination in Beaches and Estuaries: A Reference System Study in Southern California (August 2024)

    This study, funded by the San Diego Water Board and conducted in conjunction with San Diego State University, assessed traditional indicator bacteria concurrently with alternative indicators, including coliphage, HF183, adenovirus, norovirus, and pepper mild mottled virus.

    Fact Sheet – coming soon

  • Documents Associated with the San Diego River Investigative Order

    Order No. R9-2019-0014 was issued to local agencies to identify and quantify relative contributions of actual and suspected sources and transport pathways of human fecal material in dry and wet weather discharges to the Lower San Diego River Watershed.

  • Bacteria TMDL Cost Benefit Analysis (October 2017)

In August 2015, the San Diego Water Board along with representatives from the City of San Diego, Counties of San Diego and Orange, the San Diego River Park Foundation, and the San Diego County Taxpayers Association formed a Steering Committee to oversee the development of a Cost Benefit Analysis (CBA). Monthly meetings were held between August 2015 and October 2017. The specific focus of the CBA was to evaluate the infeasibility of meeting wet weather TMDL water quality objectives for bacteria indicators. The County of San Diego, County of Orange, and the City of San Diego provided the funding for the CBA. The CBA found the most effective way to meet the TMDL was to abate sources of human waste. The findings of the CBA are helping to support the San Diego Water Board, Copermittees, sewage collection system owners or operators and other entities focus efforts and resources on identifying and remediating sources of human fecal contamination.

In the winters of 2013/2014 and 2014/2015, the Southern California Coastal Water Research Project (SCCWRP) conducted a Surfer Health Study (SHS). The study focused enrollment and water quality monitoring at two beaches within San Diego city limits - Ocean Beach (located at the mouth of the San Diego River) and Tourmaline Beach, to determine whether or not the REC-1 beneficial use was supported in wet weather by measuring illness rates of surfers after their ocean exposure. The study was funded by the City and County of San Diego. The San Diego Water Board was an active member of the study’s Water Quality Advisory Committee. Results indicated gastrointestinal illness (GI) increased following periods of ocean exposure and increased even further following wet weather. Among the study population (i.e. adult and predominantly male surfers), the SHS results did not exceed the most recent USEPA guidance for recreational beaches from 2012, which recommends no more than an average 32 to 36 gastrointestinal illnesses per 1,000 swimmers.

Public Participation

The San Diego Water Board is committed to transparent and engaging community involvement in its decision-making process; inviting diverse voices and opinions can create better outcomes. The TMDL development process offers various opportunities for interested person to participate; these can include:

  • Providing data and information to the San Diego Water Board
  • Assisting in the updates/revisions to the TMDL
  • Participating in workgroups
  • Reviewing and commenting on draft TMDL language

To receive notices and opportunities for engagement on the revisions to the Bacteria TMDLs via e-mail, please subscribe to our Basin Planning mailing list: California Water Boards.

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