Part II–Designated Uses and Criteria

Total Dissolved Gas

Fresh water designated uses and criteria

Statutory Authority: Chapters 90.48 and 90.54 RCW. 03-14-129 (Order 02-14), § 173-201A-200, filed 7/1/03, effective 8/1/03.


(f) Aquatic life total dissolved gas (TDG) criteria. TDG is measured in percent saturation. Table 200 (1)(f) lists the maximum TDG criteria for each of the aquatic life use categories.


Table 200 (1)(f) Aquatic Life Total Dissolved Gas Criteria in Fresh Water

Use Category

Percent Saturation
Char Spawning and Rearing Total dissolved gas shall not exceed 110 percent of saturation at any point of sample collection.
Core Summer Salmonid Habitat Same as above.
Salmonid Spawning, Rearing, and Migration Same as above.
Salmonid Rearing and Migration Only Same as above.
Non-anadromous Interior Redband Trout Same as above.
Indigenous Warm Water Species Same as above.

(Note: spawning, rearing and migration read as spawning/rearing on Table 602. The criteria are the same)


  1. The water quality criteria established in this chapter for TDG shall not apply when the stream flow exceeds the seven-day, ten-year frequency flood.
  2. The TDG criteria may be adjusted to aid fish passage over hydroelectric dams when consistent with a department approved gas abatement plan. This plan must be accompanied by fisheries management and physical and biological monitoring plans. The elevated TDG levels are intended to allow increased fish passage without causing more harm to fish populations than caused by turbine fish passage. The following special fish passage exemptions for the Snake and Columbia rivers apply when spilling water at dams is necessary to aid fish passage:



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Last updated October 2007