The Onsite Waste Treatment Systems (OWTS) Manual provides the regulations, procedural and technical details governing individual onsite wastewater treatment systems (also referred to as septic systems). State law mandates the State Water Resources Control Board (State Water Board) adopt standards for regulation of onsite waste treatment systems (State Water Board OWTS Policy). The OWTS Manual complies with the State Water Resources Control Board OWTS Policy Tier 2 Local Area Management Program (LAMP) requirements.
View the Current OWTS Manual
June 11, 2019 Version
On June 11, 2019, the Sonoma County Board of Supervisors took action to meet State mandated septic system regulations that protect water quality and public health. The Board authorized submittal of a revised Sonoma County Local Agency Management Program (LAMP) and the OWTS Manual to the North Coast Regional Water Quality Control Board. It is anticipated the Water Board will considered for approval during their August 2019 board meeting.
May 21, 2019 Proposed Version
The proposed OWTS Manual that was considered by the Board of Supervisors on May 21, 2019. It incorporates feedback from the public.
August 31, 2018 Proposed Version
The previously proposed OWTS Manual dated August 31, 2018 incorporates feedback from the public and Board of Supervisors at the May 22, 2018 Board meeting and subsequent meetings with the Board of Supervisors Ad Hoc Committee.
September 22, 2016 Enacted Version
The OWTS Manual that was in effect from September 22, 2016 until June 30, 2019 and was replaced by the new version.