Cleanest/Best States

National Average

Dirtiest/Worst States

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

MONTANA contains a portion of 98 watersheds.

Percentage of Surface Waters with Reported Problems (state + EPA data): 11%

Number of Waterbodies with Reported Problems (as reported by the state): 869

Beneficial Use Most Frequently Impaired	Percent of All Impairments
Fish Consumption	79%
Aquatic Life Support	78%
Drinking Water Supply	26%
Primary Contact Recreation (Swimming)	25%
Agriculture	11%
Industrial	2%
Cultural	1%
Overall Use	0%

Beneficial uses not reported for 100% of waterbodies.

Priority for Regulation	Number of Waterbodies
Targeted	16
High	9
Medium	21
Low	817
Not Assessed for TMDL Priority	3
Not Reported to US EPA for TMDL Priority	3

Rivers, Streams, and Creeks
Number of impaired waterbodies: 820 (cause not reported for 0%)
Percent of Rivers, Streams and Creeks in MONTANA assessed by agencies for 1997-98 reporting period: 10%

	Percent Waterbodies Affected
Sediments	73%
Other Habitat Alterations	56%
Flow Alterations	45%
Metals	18%
Nutrients	17%
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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: 819 (cause not reported for 1%)
Percent of Rivers, Streams and Creeks in MONTANA assessed by agencies for 1997-98 reporting period: 10%

	Percent Waterbodies Affected
Agriculture	76%
Resource Extraction	26%
Silviculture	26%
Hydromodification/Habitat Modification	25%
Natural Sources	21%
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NOTE: Possible inconsistencies between data on (a) impaired waterbodies and (b) percentage of waterbodies assessed.