Wash. Rev. Code § 90.03.675
(1) A county, city, town, water-sewer district, or flood control zone district constructing, improving, operating, or maintaining stormwater control facilities under chapter 35.67, 35.92, 36.89, 36.94, 57.08, or 86.15 RCW that include stormwater retention ponds, also known as wet ponds, wet retention ponds, or wet extended detention ponds, as part of a stormwater control facility for which the primary function of the pond is to detain stormwater, must:
[ 2013 c 209 s 1.]