Marine DO Criteria


Statutory Authority: RCW 90.48.035. 06-23-117 (Order 06-04), § 173-201A-210, filed 11/20/06, effective 12/21/06.

(c) Aquatic life dissolved oxygen (D.O.) criteria. Except where noted, D.O. concentrations are measured as a 1-day minimum in milligrams per liter. Table 210 (1)(d) lists the D.O. criteria for each of the aquatic life use categories.


Table 210 (1)(d) Aquatic Life Dissolved Oxygen Criteria in Marine Water


Lowest 1-Day Minimum
Extraordinary quality 7.0 mg/L
Excellent quality 6.0 mg/L
Good quality 5.0 mg/L
Fair quality 4.0 mg/L


  1. When a waterbody's D.O. is lower than the criteria in Table 210 (1)(d) (or within 0.2 mg/L of the criteria) and that condition is due to natural conditions, then human actions considered cumulatively may not cause the D.O. of that water body to decrease more than 0.2 mg/L.
  2. Concentrations of D.O. are not to fall below the criteria in the table at a probability frequency of more than once every ten years on average.
  3. D.O. measurements should be taken to represent the dominant aquatic habitat of the monitoring site. This typically means samples should not be taken from shallow stagnant backwater areas, within isolated thermal refuges, at the surface, or at the water's edge.


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Last updated November 2007