Cleanest/Best Counties

National Average

Dirtiest/Worst Counties

0%					50%					100%

Percentage of Surface Waters with Impaired or Threatened Uses (state + EPA data):

Number of Impaired Waterbodies (as reported by the state):

NOTE: Data limitations affect the accuracy of these rankings.

Rank counties in VIRGINIA or in the U.S. by assessed use impairments.
Rank watersheds in VIRGINIA by assessed use impairments
Rank states by assessed use impairments, impairments due to specific causes, or impairments due to specific sources

LOUDOUN County contains a portion of 2 watersheds:

Middle Potomac-Anacostia-Occoquan

Middle Potomac-Catoctin

Percentage of Surface Waters with Reported Problems (state + EPA data): 24%

Number of Waterbodies with Reported Problems (as reported by the state): 94

Priority for Regulation	Number of Waterbodies
Targeted	0
High	10
Medium	6
Low	34
Not Assessed for TMDL Priority	0
Not Reported to US EPA for TMDL Priority	44

Rivers, Streams, and Creeks
Number of impaired waterbodies: 80
Percent of Rivers, Streams and Creeks in VIRGINIA assessed by agencies for 1997-98 reporting period: 39%

	Percent Waterbodies Affected
Pathogens	32%
Ammonia	30%
Organic Compounds	26%
Nutrients	19%
Sediments	15%
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NOTE: Possible inconsistencies between data on (a) impaired waterbodies and (b) percentage of waterbodies assessed.

Rivers, Streams, and Creeks
Number of impaired waterbodies: 80 (cause not reported for 33%)
Percent of Rivers, Streams and Creeks in VIRGINIA assessed by agencies for 1997-98 reporting period: 39%

	Percent Waterbodies Affected
Nonpoint Sources	45%
Impairment source not reported	34%
Unknown Sources	21%
Natural Sources	16%
Municipal Point Sources	8%
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NOTE: Possible inconsistencies between data on (a) impaired waterbodies and (b) percentage of waterbodies assessed.

Scorecard's report on

• Watershed indicators
• Toxic chemical releases from industrial facilities (TRI)
• Criteria air pollutants
• Hazardous air pollutants
• Land contamination

Drinking Water Sources for this County