Water Quality:

Identification and Remediation of Polluted Waters Impeded by Data Gaps

T-RCED-00-88: Published: Feb 10, 2000. Publicly Released: Feb 10, 2000.


Peter F. Guerrero
(202) 512-4907


Office of Public Affairs
(202) 512-4800

Pursuant to a congressional request, GAO discussed the adequacy of the data that the Environmental Protection Agency and the states have for making critical water quality decisions required by the Clean Water Act, focusing on: (1) the adequacy of the data for identifying waters for states' 303(d) lists; (2) the adequacy of data for developing total maximum daily loads (TMDL) for those waters; and (3) key factors that affect the states' abilities to develop TMDLs.

GAO noted that: (1) only 6 of the 50 states responding to GAO's nationwide survey indicated that they have a majority of the data needed to fully assess their waters, raising questions as to whether states' 303(d) lists accurately reflect the extent of pollution problems in the nation's waters; (2) while the state officials GAO interviewed feel confident that they have identified most of their serious water quality problems, several acknowledged that they would find additional problems with more monitoring; (3) states reported that they have much more of the data they need to develop TMDLs for pollution problems caused by point sources than by nonpoint sources; (4) states can more readily identify and measure point sources of pollution because these sources generally discharge pollutants through distinct points, such as pipes; (5) conversely, nonpoint sources are difficult to identify and measure because of their diffuse nature; (6) as a result, developing TMDLs for pollution problems caused by nonpoint sources often requires additional data collection and analysis; (7) only three states reported having a majority of the data they need to develop TMDLs for these types of problems; (8) states reported that they have been developing TMDLs for waters polluted by point sources for many years and, therefore, have expertise in analyzing these types of pollution problems; (9) in contrast, however, states told GAO that their ability to develop TMDLs for nonpoint sources is limited by a number of factors; (10) states overwhelmingly cited shortages in funding and staff as the major limitation to carrying out their responsibilities, including developing TMDLs; and (11) in addition, states reported TMDLs for the more complex, nonpoint sources of pollution.

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