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EPA to Consider Ocean Acidification Under Section 303(d) of Clean Water Act

April 1, 2010

EPA’s recent settlement of a lawsuit brought by the Center for Biological Diversity (Center) challenging the State of Washington’s failure to list coastal waters as “impaired” under § 303(d) of the Clean Water Act (CWA) due to reduced pH may put ocean acidification on the front line of emerging regulatory issues related to climate change. There is a growing level of scientific consensus that ocean acidification results from the reaction of atmospheric carbon dioxide with seawater, lowering the pH of the ocean, and that, “unless there are dramatic changes in fossil fuel use, projected human-driven ocean acidification over this century will be larger and more rapid than anything affecting sea life for tens of millions of years.”[1]

As part of the March 2010 settlement with the Center, EPA is currently taking comments on whether and how to address ocean acidification under the CWA, a move that could ultimately lead to the regulation of land-based activities that result in carbon dioxide emissions.[2] The settlement also commits EPA to issue guidance later this year regarding whether and how states should assess and respond to “impairments” of marine waters under the CWA.

Regulating ocean acidification under the CWA is likely to be complex and controversial. For example, listing a water body as “impaired” under CWA § 303(d) triggers a statutory duty to establish a total maximum daily load (TMDL) for the water body. A listing based on ocean acidification, therefore, would require states to quantify and control the “load” of carbon dioxide to the water body, even when those sources are regional, if not global. As a result, EPA’s decision regarding whether to treat ocean acidification under the CWA’s Impaired Waters Listing and TMDL Program could have potentially significant consequences for states, tribes, and the regulated community.

Background on Ocean Acidification and Federal Research Efforts

Ocean acidification has been referred to as “the other carbon dioxide problem.” Studies show that human activity since the beginning of the industrial revolution has resulted in an increase of atmospheric carbon dioxide concentrations from approximately 280 to 385 parts per million (ppm). The oceans have absorbed approximately 525 billion tons of carbon dioxide from the atmosphere, or about one third of the carbon emissions released from these human activities. The atmospheric concentration of carbon dioxide is now higher than experienced on Earth for at least the last 800,000 years, and is predicted to continue to rise at an increasing rate.

The absorption of carbon dioxide by the oceans has reduced greenhouse gas levels in the atmosphere and mitigated some climate change impacts, but at the cost of significant negative impacts on the chemistry and biology of the oceans. Hydrographic surveys and modeling studies reveal that the chemical changes in seawater resulting from the absorption of carbon dioxide are increasingly lowering seawater pH.[3] When carbon dioxide reacts with seawater, the reduction in seawater pH also reduces the availability of carbonate ions, which play an important role in shell formation for a number of marine organisms such as corals, marine plankton, and shellfish. This “ocean acidification” could have profound impacts on fundamental marine biological and geochemical processes in coming decades, affecting the marine food chain as well as water quality.

Ocean acidification has been the focus of increasing international study over the last several years, and the current U.S. administration has made it a research and regulatory priority. For example, following the passage of the Federal Ocean Acidification Research And Monitoring (FOARAM) Act of 2009 (Public Law 111-11), the United States is developing a strategy for an integrated national research program on ocean acidification.[4] President Obama’s Interagency Ocean Policy Task Force issued an Interim Report on National Ocean Policy in 2009 establishing a federal “stewardship principle” that “[c]urrent and future uses of ocean, coastal, and Great Lakes ecosystems and resources should be managed and effectively balanced in a way that.… recognizes environmental changes and impacts, including those associated with an increasingly ice-diminished Arctic, sea-level rise, and ocean acidification.”[5]

In April 2009, in response to the Center’s petition, EPA published a Federal Register notice[6] of information submitted to EPA on ocean acidification, and solicited additional data regarding the issue. The notice expressed EPA’s intent to determine whether to revise its decades-old national marine pH water quality criterion for the protection of aquatic life.[7] CWA § 304(a)(1) requires EPA to develop, publish, and revise water quality criteria that reflect the latest scientific knowledge.[8] The notice also solicited information and data to inform EPA’s next steps, as “well as ideas for effective strategies for Federal, State, and local officials to address the impacts of ocean acidification.”[9] EPA expects to issue a final decision regarding its evaluation of this data later this spring.

Settlement Between the Center and EPA

In August 2007, the Center submitted a letter to the Washington Department of Ecology (Ecology) requesting the listing of coastal waters due to ocean acidification. The Center argued that scientific monitoring of Washington’s coastal waters showed that the pH of some coastal waters had declined by more than 0.2 units since 2000, which is the limit for pH change due to human-caused variation under Washington’s water quality standards.[10] However, Washington’s 2008 list of impaired waters did not identify any ocean segments as impaired by acidification.

A state’s impaired waters listing is subject to EPA’s approval that existing controls are sufficient to ensure that the state’s waters meet applicable water quality standards. EPA’s disapproval of a list, in whole or in part, obligates EPA to identify waters that should be included within 30 days, and triggers the state’s TMDL requirements.[11] During EPA’s consideration of Washington’s 303(d) list, the Center submitted comment letters to EPA requesting partial disapproval of Washington’s list, and the addition of ocean waters impaired due to pH. After EPA nonetheless approved Washington’s 303(d) list in January 2009, the Center filed suit, alleging that EPA’s approval violated the CWA and the Administrative Procedure Act. The Center’s lawsuit alleged that “[a]cidified waters are already reaching surface waters in the Pacific, and ocean acidification is adversely impacting seawater quality along the Washington coast,” which has exposed “marine organisms in the surface waters, water column, and sea floor along the Washington coast” to “increasingly acidic waters.”[12] The lawsuit sought disapproval of Washington’s impaired waters list, and the addition of ocean waters as impaired due to acidification.

EPA and the Center announced the settlement of the lawsuit in March 2010. As part of the settlement, EPA published a March 22, 2010 Federal Register notice seeking comments on what considerations EPA should take into account when deciding how to address the listing of waters as threatened or impaired for ocean acidification under the CWA § 303(d) program. EPA requested comment on, among other things: (1) methods for states to monitor ocean acidification and its impacts on marine life and ecosystems; (2) how states should determine whether marine waters are impaired by acidification; and (3) recommendations for developing TMDLs for marine waters that are impaired by acidification.[13] The comment period closes on May 21, 2010. EPA intends to review the comments received and to determine how to proceed with addressing ocean acidification under the CWA § 303(d) program. Under the settlement with the Center, EPA is required to issue its decision in a memorandum by November 15, 2010.


The settlement neither forces EPA to compel the listing of marine waters as impaired due to acidification, nor to develop enforceable rulemaking related to the issue, but the Center has applauded the settlement as “a crucial step toward combating ocean acidification,” and views the CWA as one “tool in the toolbox” to push toward regulation of climate change. Even if EPA were to publish guidance that drives states to list coastal waters as “impaired” based on ocean acidification, developing reliable data of coastal waters to assess the scope of acidification may take time.[14]

Moreover, determining how states should or could address ocean acidification by regulating carbon dioxide emissions from sources well beyond the confines of a given watershed through the TMDL program could be complex and challenging, given that the scientific community has presented the causes of the problem as a global issue, and one that is well beyond the scope of individual states or regions to address.[15] The Center views the CWA as sufficiently flexible to allow for an inter-state TMDL program, as exhibited by the seven-state TMDL in the northeast designed to address atmospheric deposition of mercury,[16] and anticipates that a TMDL designed to address ocean acidification could draw on state and regional climate change initiatives. The federal government is still working out how, whether, and in what fashion to regulate in the face of increasing ocean acidification. However, some time in the not too distant future, in a repeat of prior litigation involving the Clean Air Act, a court may very well direct EPA to use its broad regulatory mandate under the CWA to take on ocean acidification.

For more information on this and other marine and climate related issues, please contact any member of Marten Law’s Fisheries, Water Quality and Climate Change practice groups.

[1] S.C. Doney, et al, Ocean Acidification: A Critical Emerging Problem for the Ocean Sciences,Oceanography, Vol. 22, No. 4, p. 24, Special Issue on the Future of Ocean Biogeochemistry in a High-CO2 World (December 2009) (“Doney”).

[2] 75 Fed. Reg. 13,537 (Mar. 22, 2010).

[3] Since the beginning of the industrial age, surface ocean pH, carbonate ion concentrations, and aragonite and calcite saturation states have been decreasing because of the uptake of anthropogenic carbon dioxide by the ocean. Surface ocean pH has already decreased by approximately 0.1 pH units, and could have a further decrease by as much 0.3-0.4 pH units by the end of this century.

[4] See L. Larson & J. Ferrell, Bounty for Land and Sea: Congress Passes Omnibus Public Lands Act, Marten Law Environmental News (Apr. 3, 2009).

[5] White House Council on Environmental Quality, The Interim Report of the Interagency Ocean Task Force at 17 (Sept. 10, 2009).

[6] 74 Fed. Reg. 17,484 (Apr. 15, 2009).

[7] Id. at 17,486. EPA’s current § 304(a) recommended criterion for marine pH is: “pH range of 6.5 to 8.5 for marine aquatic life (but not varying more than 0.2 units outside of the normally occurring range).” Id. This criterion applies to open-ocean waters within 3 miles of a state shoreline where the depth is substantially greater than the euphotic zone. Id.

[8] These criteria are based solely on data and scientific judgments on the relationship between pollutant concentrations and environmental and human health effects, and provide guidance to states in adopting water quality standards. CWA § 304(a)(2) requires EPA to develop, publish, and revise information on factors necessary to restore and maintain the integrity of waters, including the oceans, as well as protection and propagation of shellfish, fish, and wildlife, and measurement and classification of water quality.

[9] 74 Fed. Reg. at 17,484.

[10] WAC 173-201A-210(1)(f).

[11] 33 U.S.C. § 1313(d)(2); 40 CFR 130.7(d)(2).

[12] Complaint, Center for Biological Diversity v. EPA, No. 09-00670, 2-3 (W.D. Wash. 2009).

[13] See 75 Fed. Reg. 13,537, 13,538 (Mar. 22, 2010).

[14] A. Winter, Some see Clean Water Act settlement opening new path to GHG curbs, Greenwire (March 12, 2010) [subscription required].

[15] See, e.g., Doney at 24 (“Unlike many other human perturbations to the marine environment, ocean acidification is widely distributed and will influence many biogeographic regions, including open-ocean planktonic systems, coastal upwelling zones, coral reefs, high latitudes, benthic environments, and the deep sea.”).

[16] New England Interstate Water Pollution Control Commission, Northeast Regional Mercury TMDL.

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