EPA Considers Using Clean Water Act to Manage Ocean Acidification

Because greenhouse gas emissions tend to acidify ocean waters, the EPA is exploring whether the Clean Water Act can be used as a basis for regulating those emissions.

The acidity of the world’s oceans has increased by 30 percent since the beginning of the industrial age, and scientists are concerned that this decreasing pH could disrupt marine ecosystems.

It is estimated that the oceans absorb around 22 million tons of CO2 each day.

The state of Washington, where coastal waters are demonstrating particularly acute changes in acidity, recently declined to designate those waters as “imperiled.” This decision prompted the EPA’s new considerations.

Shellfish growers in the Northwest have attributed widespread deaths of oyster, clam and mussel larvae to upwelling of acidic water and are concerned that more frequent incidents could threaten their industry.

Upwelling is the wind-driven movement of CO2-rich water from deep in the ocean to the surface. Estimates are that by the end of this century, increased oceanic absorption of CO2 will make ocean water 150 times more acidic than it currently is.

Water pH is classified as a “pollutant” under the Clean Water Act, but the standard has not been revisited since it was first implemented in 1976.

Washington’s Department of Ecology declined to use this standard to designate its coastal waters as “imperiled”—which would require the development of a clean-up plan—because it said there was not enough specific data to justify doing so.

The EPA sided with Washington State’s decision. But San Francisco-based environmental group the Center for Biological Diversity, which had first initiated the request to the state, petitioned the federal agency to begin controlling ocean acidity via the authority in the Clean Water Act.

In March the EPA initiated a 60-day public comment period seeking feedback about that strategy.

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