Letters of Permission (LOP), as described in 33 CFR 325.2(e)(1), are a type of permit issued through an abbreviated processing procedure which includes coordination with Federal and state fish and wildlife agencies, as required by the Fish and Wildlife Coordination Act, and a public interest evaluation, but without the publishing of an individual public notice.

For projects subject to Section 10 of the Rivers and Harbors Act of 1899,  LOPs may beused when the District Engineer has concluded that  the proposed work would be: 1) minor; 2)  would not have significant individual or cumulative impacts on environmental values;  and 3) should encounter no appreciable opposition.

For projects subject to section 404 of the Clean Water Act, LOPs may be used after the District Engineer: 1) consultants with federal and state fish and wildlife agencies, the Regional Administrator, Environmental Protection Agency, the state water quality certifying agency and, if appropriate, the state Coastal Zone Management Agency, to develops a list of categories of activities proposed for authorization under LOP procedures; 2) issues a public notice advertising the proposed list and the LOP procedures, requesting comments and offering an opportunity for public hearing; and 3) the 401 certification has been issued or waived and, if appropriate, CZM consistency concurrence obtained or presumed either on a generic or individual basis