A line of trees, with the individual trees located less than 150 feet apart, or a tree covered area should be lighted as an extensive obstruction in the manner set forth in the "E" specifications for prominent buildings and similar extensive obstructions, with the obstruction lights mounted on poles or towers, of a height slightly greater than the height of the outstanding trees. Individual trees and widely spaced trees should be lighted in accordance with the following specifications:
Wash. Admin. Code § 468-240-180
Statutory Authority: Chapter 47.68 RCW. 96-17-018 (Order 164), recodified as § 468-240-180, filed 8/13/96, effective 9/13/96; O.M.&L. standards (part), filed 9/13/61.