Administrative Rules of Montana
Department 17 - ENVIRONMENTAL QUALITY
Chapter 17.30 - WATER QUALITY
Subchapter 17.30.6 - Surface Water Quality Standards and Procedures
Rule 17.30.655 - E-4 CLASSIFICATION STANDARDS
Universal Citation: MT Admin Rules 17.30.655
Current through Register Vol. 6, March 22, 2024
(1) Waters classified E-4 are to be maintained suitable for aquatic life, agricultural purposes, secondary contact recreation, and wildlife.
(2) No person may violate the following specific water quality standards for waters classified E-4:
(a) the acute and chronic aquatic life
standards in DEQ-7 apply;
(b) the
designated uses of a receiving water body under a different classification must
be fully maintained;
(c) the
geometric mean number of Escherichia coli bacteria may not exceed 630 colony
forming units per 100 milliliters and 10 percent of the samples may not exceed
1,260 colony forming units per 100 milliliters during any 30-day period. Water
quality criteria for Escherichia coli are expressed in colony forming units per
100 milliliters of water or as most probable number, which is a statistical
representation of the number of organisms in a sample, as incorporated by
reference in 40 CFR
136.3(b).
AUTH: 75-5-301, MCA; IMP: 75-5-301, MCA
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