Groundwater Protection:
Validity and Feasibility of EPA's Differential Protection Strategy
PEMD-93-6: Published: Dec 9, 1992. Publicly Released: Jan 12, 1993.
Additional Materials:
- Full Report:
Contact:
(202) 512-3652
contact@gao.gov
Office of Public Affairs
(202) 512-4800
youngc1@gao.gov
Pursuant to a congressional request, GAO evaluated the feasibility of protecting groundwater from pesticide contamination based on the relative vulnerability of different geographic areas.
GAO found that: (1) there were significant gaps in the data needed to conduct valid vulnerability assessments; (2) half of the states did not have data on the vadose and confining zones; (3) existing information was generally not of a sufficient degree of geographic resolution to be useful in vulnerability assessments; (4) there was great variability across states in the availability and sufficiency of the data; (5) the most extensive tests of depth, recharge, aquifer, soil, topography, impact, conductivity (DRASTIC) have found no positive relationship between DRASTIC scores and pesticide contamination; (6) a discriminant analysis approach to predict groundwater contamination was validated once and for only one pesticide; (7) none of the mathematical models were adequately validated to justify their use for developing state management plans; and (8) states generally used unvalidated methods for their assessments and, in most cases, did not verify model predictions with monitoring data.
Recommendations for Executive Action
Status: Closed - Not Implemented
Comments: Although EPA agrees with GAO's findings and conclusions, it disagrees with the recommendation. EPA has taken the position that states can conduct vulnerability assessments and develop effective pesticide management plans even though data are limited and that they must rely on best professional judgment in lieu of modeling applications.
Recommendation: Implementation of the differential protection component within the Environmental Protection Agency's (EPA) Pesticides and Groundwater Strategy should be delayed. EPA should assess the meaningfulness of preparing and evaluating these plans given the current state of the science.
Agency Affected: Environmental Protection Agency
Status: Closed - Not Implemented
Comments: Although EPA agrees with GAO's findings and conclusions, it disagrees with the recommendation. EPA has taken the position that states can conduct vulnerability assessments and develop effective pesticide management plans even though data are limited and thatthey must rely on best professional judgment in lieu of modeling applications.
Recommendation: EPA should do a pilot study with a limited number of states to assess the viability of the strategy. Issues to be addressed include the states' ability to develop meaningful plans based on differential protection and EPA ability to evaluate these plans. Until the meaningfulness of the plans can be assured, resources should not be spent on preparing them.
Agency Affected: Environmental Protection Agency
Status: Closed - Not Implemented
Comments: Although EPA agrees with GAO's findings and conclusions, it disagrees with the recommendation. EPA has taken the position that states can conduct vulnerability assessments and develop effective pesticide management plans even though data are limited and that they must rely on best professional judgment in lieu of modeling applications.
Recommendation: Until differential protection can be successfully implemented, EPA should continue its current approach of using uniform national restrictions to protect groundwater from pesticide contamination and allowing states to set standards stricter than those required by EPA.
Agency Affected: Environmental Protection Agency
Status: Closed - Implemented
Comments: EPA has indicated that it will support development of modelling methods and data development/collection methods.
Recommendation: EPA should continue to support, to the extent possible, the scientific development of the field, including state data gathering activities and the development and refinement (including validation) of vulnerability models. Only by doing this can EPA ensure that the differential protection component of its groundwater strategy will become viable.
Agency Affected: Environmental Protection Agency
Explore the full database of GAO's Open Recommendations
»
Jan 22, 2021
-
U.S. Army Corps of Engineers:
Information on the Navigation and Ecosystem Sustainability ProgramGAO-21-240R: Published: Jan 22, 2021. Publicly Released: Jan 22, 2021.
Jan 19, 2021
-
Chemical Assessments:
Annual EPA Survey Inconsistent with Leading Practices in Program ManagementGAO-21-156: Published: Dec 18, 2020. Publicly Released: Jan 19, 2021.
Jan 15, 2021
-
Environmental Liabilities:
NASA's Reported Financial Liabilities Have Grown, and Several Factors Contribute to Future UncertaintiesGAO-21-205: Published: Jan 15, 2021. Publicly Released: Jan 15, 2021.
Jan 13, 2021
-
Nuclear Waste:
Congressional Action Needed to Clarify a Disposal Option at West Valley Site in New YorkGAO-21-115: Published: Jan 13, 2021. Publicly Released: Jan 13, 2021.
Jan 7, 2021
-
Hanford Cleanup:
DOE's Efforts to Close Tank Farms Would Benefit from Clearer Legal Authorities and CommunicationGAO-21-73: Published: Jan 7, 2021. Publicly Released: Jan 7, 2021.
Dec 18, 2020
-
Drinking Water:
EPA Could Use Available Data to Better Identify Neighborhoods at Risk of Lead ExposureGAO-21-78: Published: Dec 18, 2020. Publicly Released: Dec 18, 2020. -
Recycling:
Building on Existing Federal Efforts Could Help Address Cross-Cutting ChallengesGAO-21-87: Published: Dec 18, 2020. Publicly Released: Dec 18, 2020.
Dec 9, 2020
-
Environmental Protection:
Action Needed to Ensure EPA's Enforcement and Compliance Activities Support Its Strategic GoalsGAO-21-82: Published: Dec 9, 2020. Publicly Released: Dec 9, 2020. -
Oil and Gas:
Onshore Competitive and Noncompetitive Lease RevenuesGAO-21-138: Published: Nov 19, 2020. Publicly Released: Dec 9, 2020.
Dec 7, 2020
-
Air Pollution:
Opportunities to Better Sustain and Modernize the National Air Quality Monitoring SystemGAO-21-38: Published: Nov 12, 2020. Publicly Released: Dec 7, 2020.
Looking for more? Browse all our products here