10 parts per billion would improve public health protection
Press release from the State Water Resources Control Board:
Reaching another milestone in the process of creating a maximum contaminant level (MCL) for hexavalent chromium, the State Water Resources Control Board formally proposed to set the level at 10 parts per billion (ppb), which would bring a new standard of public health protection for the state’s drinking water.
The proposal includes a three-stage compliance schedule that would provide small water systems with more time to acquire and implement the necessary water treatment technologies to meet this standard. Small systems with fewer than 10,000 connections often serve disadvantaged communities and have a smaller customer base for distributing improvement costs. As a result, they may struggle with the financial and technical challenges of installing new treatment technology for hexavalent chromium.
The formal period for public comment on the proposed regulation and the draft environmental impact report concludes on Aug. 4. The State Water Board will receive oral comments from the public at a hearing scheduled on Aug. 2. The board directly notified all of California’s over 7,000 public water systems about the proposal.
In March 2022, the board set the stage for official adoption of an MCL by announcing an administrative draft and collecting public comments. Those comments were carefully considered and helped staff refine cost considerations and specify analytical methods in the proposed regulations.
The prior MCL for hexavalent chromium was invalidated in 2017 when a court ruled the state did not adequately document if it was economically feasible for water systems to implement. The only MCL currently in place is for total chromium, which is all chromium compounds present in water, including trivalent and hexavalent chromium. This level is set at 50 ppb in California and 100 ppb federally.
“It has been a challenging path to a maximum contaminant level for hexavalent chromium that makes sense for California, but we are confident that the board can set a level that is more protective of public health than the current one for total chromium and that is economically feasible for our state’s diverse public water systems. Ultimately, protecting public health means having a standard that most systems can achieve,” said Darrin Polhemus, deputy director for the Division of Drinking Water.
Following the court’s action, the board’s Division of Drinking Water started the new quest for an MCL from scratch, using updated data and conducting a rigorous economic feasibility analysis that considered the range of impacts on water systems. Given that the costs of new technologies could be difficult for small systems, board staff included a longer implementation schedule in the proposal that allows these systems to benefit from research and development led by larger systems that must meet the standard first.
The proposed implementation period would range from two years for systems with over 10,000 service connections to four years for systems with under 1,000 connections. The board also recognizes the economic burden the regulations may place on some small water systems, many of which are already having issues with compliance and affordability. The board works extensively with many small water systems through its Safe and Affordable Funding for Equity and Resilience (SAFER) drinking water program, providing funding and technical assistance to help them serve safe and affordable drinking water. Projects that will help systems comply with primary MCLs are considered a high priority.
Commonly called chromium-6, hexavalent chromium is an odorless and tasteless heavy metal that may be found in groundwater naturally or as a result of industrial sites that failed to follow proper disposal methods for contaminated waste. Studies have linked long-term exposure to a risk of cancer when ingested. At an MCL of 10 ppb, it is estimated that a person who drinks two liters of water daily for 70 years could have a 1-in-2,000 chance of developing cancer.
If adopted by the board, the new MCL would likely take effect sometime in 2024. The State Water Board’s mission is to preserve, enhance and restore the quality of California’s water resources and drinking water for the protection of the environment, public health, and all beneficial uses, and to ensure proper resource allocation and efficient use for the benefit of present and future generations.
