Sewer Use and Local Limits Ordinance Update
Under its National Pollutant Discharge Elimination System Permit (CA0056294, Order No. R4-2019-0137), which was adopted by the Los Angeles Regional Water Quality Control Board (LARWQCB) on November 14, 2019, and became effective on January 1, 2020, and regulates the Hill Canyon Treatment Plant (HCTP), the City conducted a technical evaluation of its current local limits. The City’s consultant recommended the local limits be updated since they were based on conditions prior to 1994. Since the development of the current local limits, there have been significant changes to the HCTP, industrial user base, regulations, and other factors that warrant a local limits update. A final draft of the Local Limits Report was completed in October 2023. The proposed local limits will increase for selenium, silver, and total dissolved solids and decrease for arsenic, biochemical oxygen demand, cadmium, chloride, chromium, copper, cyanide, lead, mercury, nickel, and total suspended solids. New local limits are proposed for ammonia as nitrogen, molybdenum, and sulfate as SO4. The local limits will remain the same for boron and zinc. The City proposes to remove the current local limits for fluoride, phenols (total), sulfide, and total identifiable chlorinated hydrocarbons.
The City is also updating the Sewer Use Ordinance in its Municipal Code. The revised Sewer Use Ordinance consolidates all sewer use requirements into one article and updates language to meet federal requirements. Wastewater discharge permits will be tiered to better define the obligations required of wastewater dischargers depending on the level of threat of a discharge. Public Review Period: This notice serves as the notice of request for approval of a pretreatment program substantial modification as required by Title 40 of Code of Federal Regulation (CFR) 403.18(b)(2) and 403.11(b)(1)(i).
Persons wishing to comment upon or object to the proposed modifications can submit comments in writing by 5:00 p.m. on March 24, 2025, to: Paul Jorgensen at the City of Thousand Oaks, Public Works Department, 2100 Thousand Oaks Boulevard, CA 90013, Thousand Oaks, CA 91362, and Adam Taing at LARWQCB, 320 W. 4th Street, Suite 200, Los Angeles, or email comments to pjorgensen@toaks.gov and adam.taing@waterboards.ca.gov. For e-mail comments, include “Thousand Oaks Sewer Use Ordinance Substantial Modification” or “Thousand Oaks Pretreatment Program Local Limits” in the subject line.
All comments received prior to or on that date will be considered in the final determinations regarding the modification. If no substantive comments are received prior to or on March 24, 2025, the LARWQB will conditionally approve the City’s proposed request without change.