California water board officials have delayed for the second time this year voting on a proposed rule to prohibit "wasteful water use practices" statewide, after numerous water supply agencies and water rights holders recently raised legal and policy objections to the plan.

California air board chief Mary Nichols is attacking President Trump's recent order for U.S. EPA Administrator Scott Pruitt to take a series of "actions" to accelerate and ease state and industry compliance with national ambient air quality standards (NAAQS), saying the move could lead to "unhealthy people, shortened lives, and greater demands on our health care system."

A Senate Republican has introduced a resolution urging the California Legislature to "abandon" consideration of a "pay-per-mile" tax on motorists to reduce air pollution, arguing that such a levy would burden hundreds of thousands of drivers with long commutes and who already pay the highest gasoline prices and some of the highest associated taxes in the nation.

Attorney General Xavier Becerra (D) and the California Air Resources Board (ARB) are suing U.S. EPA over its decision to scrap a long-running "once in, always in" policy that requires facilities meet strict "major source" maximum achievable control technology (MACT) "major source" air toxics limits even if their emissions fall below MACT levels.

U.S. EPA and environmental justice groups are at odds over how a federal judge should implement her sharply worded order finding the agency violated its regulatory requirements to issue preliminary findings responding to several Civil Rights Act (CRA) discrimination petitions within 180 days, with the parties split over whether EPA has a mandatory duty to respond to such petitions within the deadline.