Timothy Bishop (D-NY) and Eddie Bernice Johnson (D-TX), the Ranking Member and Member respectively, of the Subcommittee on Water Resources and Environment of the House Transportation and Infrastructure Committee.
Atmospheric deposition, a process that transfers pollutants, including NOx, SO2, and mercury, from the air to the earth's surface, can significantly impair the quality of the nation's waters. EPA can potentially address atmospheric deposition through the Clean Water Act (CWA) and the Clean Air Act (CAA), but concerns have been raised about its ability to do so. GAO was asked to examine EPA's efforts to address atmospheric deposition of pollutants that impair waterbodies. The report examines: (1) the extent to which atmospheric deposition of NOx, SO2, and mercury contributes to the impairment of the nation's waters and identify the key sources of these pollutants; (2) the regulatory tools that EPA uses under the CWA to address the effects of atmospheric deposition, and the challenges, if any, that it faces in doing so; and, (3) the regulatory tools that EPA uses under the CAA to address the effects of atmospheric deposition, and the challenges, if any, that it faces in doing so. To conduct the work, GAO reviewed EPA data, reports, and activities and interviewed agency officials and other experts.
GAO indicates that it found that atmospheric deposition of nitrogen oxides (NOx), sulfur dioxide (SO2), and mercury contributes to the impairment of the nation's waters, but the full extent is not known. For example, states provide EPA with data on the extent to which their waterbodies do not meet water quality standards, and some states have reported that some of their waterbodies are polluted because of atmospheric deposition. However, the states have not assessed all of their waterbodies and are not required to report on the sources of pollution. Similarly, Federal studies show that atmospheric deposition of NOx, SO2, and mercury is polluting waterbodies but have data for only some waters. The main sources of NOx and SO2 are cars and other forms of transportation and coal-burning power plants. Power plants are also the largest U.S. source of mercury emissions, but international sources also contribute to the mercury deposited in U.S. waters. GAO indicates that EPA has sought to address atmospheric deposition through Clean Water Act (CWA) programs but faces challenges in doing so. Specifically, states typically establish water quality standards -- considering EPA recommended criteria -- for each waterbody. If a waterbody does not meet standards, CWA generally requires the state to set a Total Maximum Daily Load (TMDL) that identifies the maximum amount of pollutant that can enter the waterbody and still meet standards. States are responsible for taking actions to ensure the TMDL is met. For point sources of pollution, such as a pipe from a sewer treatment plant, CWA requires new or renewed permits to be consistent with the TMDL. However, there is no similar statutory requirement for nonpoint sources of pollution, such as atmospheric deposition. States may take actions, such as providing technical or financial assistance to limit pollution from nonpoint sources, but face a challenge when atmospheric deposition pollution affecting their waters originates in emissions from a different state.
EPA has also sought to address atmospheric deposition through Clean Air Act (CAA) regulations but also faces challenges in doing so. EPA issued regulations that reduced emissions of NOx, SO2, and mercury and in turn the amount of pollution in waterbodies. Even with reduced emissions, NOx, SO2, and mercury continue to pollute the nation's waterbodies. EPA's recent attempt to address atmospheric deposition by establishing secondary National Ambient Air Quality Standards (NAAQS) -- standards to protect public welfare -- targeting the effects of acid rain caused by NOx and SO2 on water bodies was not successful. EPA stated that uncertainty regarding atmospheric modeling and limitations in available data prevented determination of secondary NAAQS adequate to protect against the effects of acid rain, and the agency has not identified alternative strategies. EPA has begun a 5-year pilot program to gather additional scientific data, but it is unclear whether or when the agency will be able to address scientific uncertainties to enable adoption of a protective secondary NAAQS. EPA also did not set secondary NAAQS to address nutrient over-enrichment in aquatic ecosystems caused by NOx because of the limited available scientific data. Many sources of nitrogen can contribute to nutrient over-enrichment in a waterbody, including sources of nitrogen unrelated to atmospheric deposition. EPA recently announced an effort that is to lead to the development of an integrated nitrogen research strategy that includes approaches to reducing atmospheric deposition of NOx into waters impaired because of nutrient over-enrichment by nitrogen.
GAO recommends that EPA determine whether EPA can obtain in a timely manner the data it needs to establish secondary NAAQS adequate to protect against the effects of acid rain and, if not, identify alternative strategies to do so. EPA agreed with GAO's recommendation.
In the report conclusions, GAO indicates that, "EPA has long recognized atmospheric deposition as a problem and has sought to mitigate its effects; however, EPA's efforts are being hindered by limitations in the regulatory tools available to it. The CAA provides EPA with regulatory tools to reduce airborne emissions -- and this has reduced atmospheric deposition. Even with these reductions, atmospheric deposition continues to affect water quality and harm aquatic ecosystems. One CAA tool for airborne emissions is also currently available to EPA to directly address the effects of atmospheric deposition -- secondary NAAQS -- but EPA has not been successful in using secondary NAAQS to protect water quality and aquatic ecosystems from acid rain or nutrient over-enrichment.
"We acknowledge the innovative approach EPA developed for establishing secondary NAAQS to address acid rain. However, as of April 2012, EPA stated it did not have sufficient scientific data to determine with an acceptable degree of scientific certainty if its new approach would meet applicable legal standards to establish the secondary NAAQS. Further, the 5-year pilot program it has initiated to inform future reviews of NAAQS to address acid rain is not designed specifically to obtain these data. However, EPA has not identified alternative strategies to address the acidification of aquatic ecosystem if it cannot resolve the scientific uncertainties that prevented it from issuing the secondary NAAQS in April 2012. Furthermore, secondary NAAQS may not be well suited to address acid rain because EPA must satisfy the legal requirement that secondary NAAQS provide the requisite degree of protection -- that is, that the standards are neither more nor less stringent than necessary -- for all parts of the nation, and some areas of the nation are sensitive to the effects of acid rain, while others are naturally resistant to them.
"Additionally, EPA does not have the scientific data it needs to establish a secondary NAAQS to address the contribution of NOx to nutrient overenrichment in aquatic ecosystems. Because there can be many sources of nitrogen that contribute to nutrient over-enrichment in a waterbody, including sources of nitrogen unrelated to atmospheric deposition, secondary NAAQS by themselves may not be well suited to address nutrient over-enrichment. EPA announced in 2012 that it will develop a "Nitrogen Roadmap" that identifies how it will foster research, program implementation, and policy integration for nitrogen and other pollutants across the agency. This roadmap is intended to be a scoping document that is to precede more concrete steps to develop an integrated nitrogen research strategy to address nutrient over-enrichment. We encourage EPA to continue its effort to develop an integrated nitrogen research strategy, which may lead to more suitable approaches to address nutrient over-enrichment.
"Regarding mercury, because most emissions originate outside of the United States, EPA's regulatory tools are of limited applicability to the majority of emissions, but the agency is involved in the UNEP negotiations to, among other things, reduce atmospheric emissions of mercury on a global scale. This will be an important step toward reducing mercury levels in our nation's waters."
Access the complete 59-page report (click here). [#Water, #Air]
GET THE REST OF TODAY'S NEWS
Want to know more about WIMS? Check out our LinkedIn company website (click here). 33 Years of Environmental Reporting for serious Environmental Professionals
No comments:
Post a Comment