Onsite Wastewater Treatment Systems

Policy Implementation Program


California has more than 1.2 million onsite wastewater treatment systems (OWTS). Over 40% of these are in the Central Valley. OWTS are typically domestic systems in areas without centralized sanitary sewers; most do not pose a significant threat to human health and water quality. However, poorly sited, designed, and maintained OWTS can impact shallow groundwater, primarily with nitrates and pathogens. In 2000, Governor Gray Davis codified California Water Code §13290 et. seq., a modified form of Assembly Bill 885, due to related public concerns. These sections directed the State Water Resources Control Board (State Board) to adopt standards or regulations for OWTS by 1 January 2004. State Board released draft standards in 2005, but strong public opposition prevented their adoption. On 19 June 2012, State Board adopted Resolution No. 2012-0032, which includes the Water Quality Control Policy for Siting, Design, Operation and Maintenance of Onsite Wastewater Treatment Systems (OWTS Policy).

The goal of the OWTS Policy is to correct and prevent system failures due to poor siting and design, and excessive OWTS densities. The OWTS Policy recognizes that Local Agencies, typically county health departments, have greatest regulatory expertise; they will remain as leads. Local Agencies have historically focused on public health. The OWTS Policy adds new focus on water quality protection, and has a risk-based approach for new, replacement, and failing OWTS. Four risk tiers require increasing Regional Board oversight of Local Agencies: Tier 0 covers properly functioning, existing OWTS up to 10,000 gallons per day of projected flow. These require no changes in local codes and ordinances. Tier 1 covers low-risk new and replacement OWTS up to 3,500 gallons per day with conservative, largely prescriptive standards. Tier 2 covers new and replacement OWTS up to 10,000 gallons per day that do not meet Tier 1 standards. For these, Local Agencies have the option to propose Local Agency Management Programs (LAMPs) for Regional Board approval. These are alternative standards overall as protective of human health and water quality as Tier 1. Tier 3 are OWTS less than 600 feet from Clean Water Act 303(d) listed impaired water bodies for nitrates and pathogens. For such areas, LAMPs must include Advanced Protection Management Programs (APMPs). Tier 4 covers failing OWTS, for which the Policy specifies minimum corrective actions.

Tier 2 LAMPs are the OWTS Policy's key focus. LAMPs are conditional waivers of Waste Discharge Requirements. Subject to California Water Code §13269, LAMPs must be consistent with Basin Plans, in the public interest, and not to exceed five years in duration. Section 9 of the OWTS Policy provides minimum standards; considerations for siting and design, record keeping, and reports to Regional Boards.

The Central Valley has 30 Local Agencies that sent our agency Letters of Intent to submit LAMPs. Of these, 29 submitted draft LAMPs by the 13 May 2016 Policy deadline. On 8 March 2019, the remaining Local Agency, Lake County, submitted an informal draft. Our Region's review procedures are: 1) seek comments from State Water Resources Control Board Division of Drinking Water on proposed notifications (i.e., of OWTS failures, installations, and repairs near public water supplies), 2) review LAMPs in detail with a Preliminary Completeness Checklist to identify issues, 3) resolve issues with the Environmental Health Director (and external Water Board Regions, as warranted), 4) request the Director to seek local Board of Supervisors' (BOS) approval and adoption of related new codes and ordinances, 5) publicly notice BOS approved LAMP for our Regional Board's consideration, and 6) address public comments and seek Regional Board approval. To date, our Regional Board has approved all LAMP submittals. Two include APMPs, for Wolf and Wood Creeks, respectively in Nevada and Tuolumne Counties. Central Valley Water Board staff are working closely with the Lake County Environmental Health Director toward LAMP completion and approval.

Central Valley Local Agencies with Regional Board approved LAMPs have begun implementation, which began 13 May 2018. Pursuant to the OWTS Policy, all Local Agencies shall submit their first Annual Reports on 1 February 2019. Local Agencies with approved LAMPs shall submit their first Water Quality Assessment Reports on 1 February 2023. In 2019, staff received 31 Annual Reports, 94% within one week of the deadline. Due to the Camp Fire, staff extended deadlines to the County of Butte and Town of Paradise. Rather than allow the Fresno County LAMP to regulate their jurisdictional OWTS, the Cities of Clovis and Fresno opted for Tier 1 and must therefore submit independent Annual Reports. The City of Fresno's Report is delinquent, therefore staff are considering potential enforcement. Staff are collaborating with the California Conference of Directors of Environmental Health and State Board on report formatting, data analysis in ArcGIS, and key content of pending Water Quality Assessment Reports.

Program Information

Local Agency Management Programs (LAMPs)

Local Tier 2 standards, alternative to those in Tier 1 as described in the State Water Resources Control Board Water Quality Control Policy for Siting, Design, Operation, and Maintenance of Onsite Wastewater Treatment Systems (OWTS Policy), Sections 7, 8, and 9.

Basin Plan Amendments to Incorporate the OWTS Policy

(amends the Basin Plans to remove current septic tank guidelines and incorporate the OWTS Policy)

Prohibition Orders

Central Valley Regional Water Quality Control Board Prohibitions for leaching systems, as listed in:
NOTE:  For Fresno and Tulare Counties, local moratoria prohibit new OWTS in the following areas:
  • Fresno County - Del Rio
  • Tulare County - Delft Colony, El Rancho, Lindcove, Poplar, Seville, Tonyville, Tooleville, Traver, Wells Tract, and Yettem

Subscribe to our Onsite Wastewater Treatment Systems Policy Implementation Program email list to receive notifications and the latest updates. After subscribing, you will need to check your email host for a confirmation email to complete the subscription.

Email Address: (required)
Your Full Name: (required)
(e.g. John Smith)

  Subscribe to our other email lists.

Contact Us