EPA approves mercury limits for California salmon

WASHINGTON, D.C. — The federal government, in an attempt to protect sportfishing, subsistence fishing and tribal cultural use, announced July 18 it established new water quality criteria for mercury in California waters.

A new Environmental Protection Agency (EPA) mandate would place limits on mercury found in salmon fish tissue as part of a public health initiative.

“The state’s new rules set five new water quality criteria for mercury in fish tissue for tribal subsistence fishing, general subsistence fishing, prey fish, sport fish and for fish commonly consumed by the protected California Least Tern. The new criteria will help protect and inform the public about levels of mercury in popular sport fish like salmon, bass, sturgeon and trout,” EPA spokesperson Soledad Calvino said in a released statement.

Updated water quality objectives were specifically mandated in five categories: sportfishing; tribal subsistence fishing; general subsistence fishing; prey fishing; and, California least tern prey fishing.

The EPA mandate, specifically targeting methylmercury, limits mercury levels found in salmon to 0.02-0.05 milligrams per kilogram, depending on the specific category of fishing type. Small traces of methlymercury, commonly found in fish and shellfish tissue, exist in the human body. However high levels of the neurotoxin can pose serious health risks, such as loss of peripheral vision and muscle weakness, according to the EPA.

EPA’s mercury restrictions apply to enclosed bays, estuaries and inland surface waters in Northern California, including Cache Creek, Clear Lake, the Delta and San Francisco Bay.

Heightened levels of neurotoxin were poured into state waterways during California’s Gold Rush era, when mining companies, according to the EPA, “released millions of pounds of naturally occurring mercury.”

Morgan Bond, NOAA photo

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