pH Criteria for Surface Water Quality Standards

Washington State Department of Ecology

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Part II–Designated Uses and Criteria

pH

173-201A-210

Marine water designated uses and criteria.

Statutory Authority: Chapters 90.48 and 90.54 RCW. 03-14-129 (Order 02-14), § 173-201A-210, filed 7/1/03, effective 8/1/03.

(g) Aquatic life pH criteria. Measurement of pH is expressed as the negative logarithm of the hydrogen ion concentration. Table 200 (1)(g) lists the pH levels for each of the aquatic life use categories.

Table 210 (1)(g) Aquatic Life pH Criteria in Fresh Water

Use Category	pH Units
Extraordinary quality	pH must be within the range of 7.0 to 8.5 with a human-caused variation within the above range of less than 0.2 units.
Excellent quality	pH must be within the range of 7.0 to 8.5 with a human-caused variation within the above range of less than 0.5 units.
Good quality	Same as above.
Fair quality	pH must be within the range of 6.5 to 9.0 with a human-caused variation within the above range of less than 0.5 units.

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Last updated December 2007