POLLUTION LOCATOR|Explanation of Water Quality Ranking Criteria

Scorecard ranks states, counties, and watersheds by various water quality measures. Specific ranking criteria are defined below, with links to more information if you need it. Note: Data limitations affect the accuracy of these rankings.

RANK BY ASSESSED USE IMPAIRMENT
Scorecard ranks states, counties and watersheds by the percentage of surface waters with impaired or threatened uses and by the number of impaired waterbodies. These measures indicate the extent to which waters in an area do not attain water quality standards.

RANK BY IMPAIRMENTS DUE TO A SPECIFIC CAUSE
Scorecard ranks areas by the number of waterbodies that do not attain water quality standards due to specific causes such as sediments, nutrients, pesticides, or metals. Waterbodies are classified into four types: Rivers, Streams, and Creeks; Lakes, Reservoirs, and Ponds; and Estuaries, Bays, and Coasts; Fresh Water Wetlands.

RANK BY IMPAIRMENTS DUE TO SPECIFIC SOURCES
Scorecard ranks areas by the number of waterbodies that do not attain water quality standards due to specific sources such as agriculture, industrial discharges or sewage treatment systems. Waterbodies are classified into four types: Rivers, Streams, and Creeks; Lakes, Reservoirs, and Ponds; and Estuaries, Bays, and Coasts; Fresh Water Wetlands.