State Water Board Adopts Rulemaking for Chromium-6 MCL by ACWA Staff Apr 17, 2024 The State Water Resources Control Board today adopted a new Maximum Contaminant Level (MCL) of 10 parts per billion (ppb) for Hexavalent Chromium (Chromium-6) in drinking water. The regulation applies to all water suppliers, including small public water systems (PWS). Prior to taking effect, the regulation must first be approved by the Office of Administrative Law. Once approved, it is expected that the regulation will take effect by October. Water suppliers will be required to comply with the regulation in accordance with the following specified timelines: PWS with 10,000 or more connections will be required to comply within two years after the MCL takes effect; PWS with 1,000-9,999 connections will be required to comply within three years after the MCL takes effect; and PWS with less than 1,000 connections will be required to comply within four years after the MCL takes effect. ACWA and its coalition partners have engaged with State Water Board and its staff on this process for several years, including providing public comments at today’s hearing. Staff shared appreciation for the added compliance timeline flexibility and encouraged the State Water Board to continue to look at financial and technical support — as well as consider unique circumstances — for water systems in disadvantaged communities and low-income communities that are working towards compliance but will be challenged to do so in the time provided.
