Water Quality: Inconsistent State Approaches Complicate Nation's Efforts to Identify Its Most Polluted Waters.

摘要

The approaches used to identify impaired waters vary considerably among states. Variation among the states stems from a combination of factors, including differences in the (1)water quality standards (including designated or beneficial uses and criteria)for determining which waters are impaired;(2)types of monitoring practices used to ascertain whether these standards are exceeded;(3)procedures used to assess water quality data to make listing decisions;and (4)guidance EPA regions give on grounds for removing waters from state lists of impaired waters. This variation leads not only to inconsistencies in the listing of impaired waters but also to difficulties in identifying the total number of impaired waters nationwide and the total number of TMDLs that states say will be needed to bring such waters up to standards. Of particular note,there have been numerous cases in which neighboring states share a common body of water that is listed as impaired by one state but not by the other. Under the Clean Water Act and its regulations, EPA has provided some flexibility to states to develop listing approaches that are appropriate to their ecological and other conditions. However, some of the variations in approaches have no appropriate scientific basis. EPA has published one set of guidance that it believes will address some of these inconsistencies. It is also planning to issue a second set of guidance to improve consistency among state approaches and in state methodologies.