EPA Impaired Waters Listing May Open Door To Mississippi Nutrient LimitsBy Inside EPA
23 August 2011
EPA is poised to decide in the coming weeks whether to list coastal waters in Louisiana as impaired for dissolved oxygen (DO), a decision that environmentalists hope could begin a regulatory process to restrict nutrients in upstream Mississippi River Basin waters even though the agency recently denied activists’ petition to require such limits. But environmentalists are also pushing EPA to give a higher priority ranking to the waters, which would require actions more quickly to address the pollution, as well as arguing for EPA to list the coastal waters as impaired for nutrients, which would more directly address the source of the impairment and is consistent with Science Advisory Board advice. The agency earlier this year sent a letter to the Louisiana Department of Environmental Quality (LDEQ) disapproving of the state’s "decision not to list three coastal waters west of the Mississippi River mouth which are affected by low levels of dissolved oxygen."
While LDEQ found that the three coastal segments were not meeting dissolved oxygen criteria, the state designated the waters as category 4b, a classification for waters that are impaired but for which pollution limits, known as a total maximum daily load (TMDL), is not needed because other controls will lead to meeting water quality standards. "EPA agrees with LDEQ’s decision that the three coastal segments . . . are not meeting the applicable marine dissolved oxygen criteria. However, EPA disagrees with the State’s decision that these water quality limited segments are exempt from the TMDL process.
"Consequently, EPA insists that the agency add the segments to the state’s Clean Water Act (CWA) section 303(d) impaired waters listing, meaning that a TMDL would be required. The agency also assigned the waters "priority ranking," environmentalists note, though they argue it is not high enough.EPA is now considering comments and hopes by the end of the month to finalize its decision in the Federal Register, according to an EPA source. Under section 305(b) of the Clean Water Act (CWA), states are required to assess the water quality status of waterbodies within their boundaries. EPA encourages states to use a five category system to classify which waters are meeting water quality standards. Those waters that are not meeting the standards are listed as being impaired, as required by CWA section 303(d), and can then be subject to control requirements, such as TMDLs.
Sources say that should EPA finalize its decision to list the waters as impaired, it could act as a hook to regulate upstream waters that may be contributing to the impairment, beginning the process of cutting down on nutrient pollution in the Mississippi Basin that contributes to the large hypoxic Dead Zone in the Gulf of Mexico. Low levels of DO can be a function of high nutrient levels, because the nutrients encourage eutrophication. For example, one activist says that listing the waters as impaired under 303(d) would require a TMDL, which will set a cap on pollution in the Gulf that could target upstream sources of pollution, "given the fact that the majority of the sources