A letter of permission is a type of individual permit issued through a streamlined processing procedure compared to standard individual permits. The Seattle District issues LOPs in Section 10 Navigable Waters of the U.S. only; LOPs are not applicable for work subject to Section 404 of the Clean Water Act.
An LOP may be issued in cases where proposed work would be minor, would not have significant individual or cumulative impacts on environmental values, and should encounter no appreciable opposition.
The types of projects often considered minimally impacting include minor dredging and construction, maintenance, or replacement of piers, mooring buoys, piles, or floats.
Compliance reviews under Section 7 of the Endangered Species Act and Section 106 of the National Historic Preservation Act still apply.
In addition, notification of the project is sent to the National Marine Fisheries Service, U.S. Fish and Wildlife Service, Washington State Department of Ecology, and local tribal interests for comments in lieu of a public notice.