(a) Portion declared nonnavigable
That portion of Back Cove at Portland, Maine, lying southerly of a line across the twelve-foot Federal project channel in Back Cove twenty-five hundred feet upstream from the Tukey Bridge, to the head of Back Cove, is declared to be a nonnavigable water of the United States within the meaning of the Constitution and laws of the United States.

(b) Portion abandoned
That portion of the twelve-foot Federal project channel in Back Cove lying southerly of a line across the channel twenty-five hundred feet upstream from the Tukey Bridge, to the head of Back Cove, a distance of approximately thirty-five hundred feet, is abandoned.

(c) Preservation of right to alter, amend or repeal section
The right to alter, amend, or repeal this section is expressly reserved.