February 16, 2023, the State Water Resource Control Board (SWRCB), Division of Drinking Water (DDW) announced a proposal to lower the Notification Level (NL) for manganese to 20 µg/L (current NL is 500 µg/L). DDW is proposing to lower the manganese Response Level (RL) to 200 µg/L (the current RL is 5,000 µg/L).
The DDW announcement states “These levels are based on adverse neurotoxicological effects seen in laboratory animals exposed to manganese.”
DDW indicates that an informational item on the proposed manganese NL and RL is planned for the SWRCB’s March 21, 2023 meeting (the Agenda for the SWRCB’s March 21, 2023 meeting has not yet been posted).
Link to proposed manganese NL and RL and supporting documentation (at this location, scroll down to the table for the manganese entry): https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/NotificationLevels.html.
