Part II–Designated Uses and Criteria

Turbidity

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 turbidity criteria. Turbidity is measured in "nephelometric turbidity units" or "NTUs." Table 210 (1)(e) lists the one-day maximum turbidity allowed as a result of human actions for each of the aquatic life use categories.

 

Table 210 (1)(e) Aquatic Life pH Criteria in Marine Water

Use Category

NTUs
Extraordinary quality Turbidity must not exceed:
  • 5 NTUs over background when the background is 50 NTU or less; or
  • A 10 percent increase in turbidity when the background turbidity is more than 50 NTUs.
Excellent quality Same as above.
Good quality Turbidity must not exceed:
  • 10 NTUs over background when the background is 50 NTUs or less; or
  • A 20 percent increase in turbidity when the background turbidity is more than 50 NTUs.
Fair quality Same as above.
  1. The turbidity criteria established under WAC 173-201A-210 (1)(e) shall be modified, without specific written authorization from the department, to allow a temporary area of mixing during and immediately after necessary in-water construction activities that result in the disturbance of in-place sediments. This temporary area of mixing is subject to the constraints of WAC 173-201A-400 (4) and (6) and can occur only after the activity has received all other necessary local and state permits and approvals, and after the implementation of appropriate best management practices to avoid or minimize disturbance of in-place sediments and exceedances of the turbidity criteria. A temporary area of mixing shall be as follows:
    1. For waters up to 10 cfs flow at the time of construction, the point of compliance shall be one hundred feet downstream from the activity causing the turbidity exceedance.
    2. For waters above 10 cfs up to 100 cfs flow at the time of construction, the point of compliance shall be two hundred feet downstream of the activity causing the turbidity exceedance.
    3. For waters above 100 cfs flow at the time of construction, the point of compliance shall be three hundred feet downstream of the activity causing the turbidity exceedance.
    4. For projects working within or along lakes, ponds, wetlands, estuaries, marine waters or other nonflowing waters, the point of compliance shall be at a radius of one hundred fifty feet from the activity causing the turbidity exceedance.

       

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Last updated December 2007