![]() Feasibility study to evaluate and screen treatment and facility siting alternatives.Field testing of wells to determine the potential for Chrome 6 source control.Using the mitigation/treatment approach, the City completed the following steps: ![]() Approval at the Office of Administrative Law (OAL) is still to be determined.įollowing the Jadoption (since rescinded) of the Chrome 6 MCL by DDW, the City initiated quarterly monitoring for Chrome 6 in their potable wells and submitted a Corrective Action Plan (CAP) outlining the steps and estimated timeframe needed to achieve Chrome 6 compliance. This MCL includes a compliance schedule based on water system size and requirements to submit compliance plans and operations plans under certain conditions. In June 2023, th e State Water Board released the Notice of Proposed Rulemaking for the Hexavalent Chromium MCL and associated Draft Environmental Impact Report. A hearing is scheduled on Augand written comments are due August 4, 2023. More information is available in the Notice of Preparation. The Division of Drinking Water is soliciting early public consultation via a scoping meeting to be held virtually on November 29th at 3pm. The Notice of Preparation of an environmental impact report is available. Preliminary occurrence data and treatment cost estimates were released in October and November 2020, with public workshops on the cost estimates held on December 8 and 9, 2020. The public comment period ended on May 15, 2020. On April 27, 2020, State Water Board staff held a public workshop on the White Paper. In February 2020, the State Water Board staff published the White Paper Discussion on Economic Feasibility Analysis in Consideration of a Hexavalent Chromium Maximum Contaminant Level. The regulation of hexavalent chromium in drinking water reverts back to the previous State of California MCL of 50 ppb for Total Chromium, to which the city is in compliance.Īlthough the MCL was rescinded, the court ordered the State Water Board to adopt a new MCL for hexavalent chromium. Therefore, as of Septemthe 10 ppb MCL for Cr6 is no longer in effect. This change became effective on September 11, 2017. The court ordered the Water Board to delete the new hexavalent chromium MCL from the California Code of Regulations. The court determined the State Water Resources Control Board (Water Board) failed to properly follow the requirements of the Safe Drinking Water Act for establishing the new MCL. In May 2017, the Superior Court of Sacramento County issued a judgment invalidating the new California MCL of 10 ppb for Cr6. State Rescinds 2014 MCL for Hexavalent Chromium Therefore, DDW determined that communities with groundwater wells exceeding the new MCL could continue to use those wells while they implemented proposed system improvements to address Cr6 under compliance plans approved by DDW. Any potential health risks regarding Cr6 in drinking water would require decades of drinking large volumes of drinking water with elevated levels of Cr6. DDW was careful to point out that the new 10 ppb MCL did not create an urgent drinking water crisis. The new MCL was adopted at 10 micro-grams per liter, or 10 parts per billion (ppb). In 2014, the State of California created a new maximum contaminant level, or MCL, for hexavalent chromium. Patterson is in compliance with this standard.Ģ014 California Regulation for Hexavalent Chromium 50 ppb is the total chromium MCL for the state of California set by the State Water Resources Control Board, Division of Drinking Water (DDW), and is still in effect.Total chromium includes both trivalent chromium (chromium 3) and hexavalent chromium (chromium 6). 100 parts per billion (ppb) is the federal maximum contaminant level (MCL) set by the EPA for total chromium.The following information on chromium levels can be helpful to keep in mind: The City of Patterson's water supply currently averages between 14.2 and 20.3 parts per billion – far BELOW the levels set by the State and current Federal limits. However, Patterson’s water has always had a small trace amount of chromium 6 that is naturally occurring and not caused by industrial contaminants. Hexavalent chromium, in high doses, can be identified as a carcinogenic. The most common forms of chromium that occur in natural waters are trivalent chromium (chromium 3) and hexavalent chromium (chromium 6). Chromium is found naturally in rocks, plants, humans and animals.
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