The State Water Resources Control Board adopted rules on May 3 to protect people and wildlife consuming fish from freshwater streams, lakes and rivers in California that contain mercury— a potent neurotoxin.
“Fish like salmon, bass, sturgeon and other popular fish like trout are sought after as a key food source by California Native American tribes, and other groups that depend on fish for sustenance,” said State Water Board Chair Felicia Marcus. “Our goal in updating the rules is to more clearly identify who depends on such fish in their diet and where, and then focus our attention on what can be done to limit those exposures. Unfortunately, mercury can be found in many fresh water bodies in California and are largely a legacy of the Gold Rush era and difficult to resolve. Longer lived fish, like bass and sturgeon, tend to accumulate the most mercury.”
The rules establish new “beneficial use” definitions to protect California Native American cultural and subsistence fishing uses and non-tribal subsistence fishing uses. Based on these uses, the rules set protective levels of methylmercury in fish tissue and an implementation plan for achieving those levels.
The primary goal of the proposed mercury amendment is to restore and improve the chemical, physical and biological integrity of California’s water bodies by reducing levels of mercury in order to support the beneficial uses of fish consumption by humans and wildlife and to define beneficial uses to protect California Native American tribal uses, according to the Water Board.
Although mercury occurs naturally in the environment, mercury concentrations exceed background levels due to human activities. Gold and mercury mines, atmospheric deposition, industrial and municipal wastewater discharges, and urban storm water runoff are all sources of mercury that can enter surface water bodies and accumulate in fish tissue to levels that can be toxic to humans and wildlife.
The Board’s action sets what are called “water quality objectives,” which are required to establish safe consumption levels for fish that are known to have accumulated mercury.
Source: State Water Resources Control Board
