53 Pa. Stat. § 2862
Any municipality may erect or construct dikes, river bank protection, and other flood control works, and may widen, deepen, straighten, and otherwise improve the channels and banks of creeks, streams, and rivers, within or without its territorial limits and within or without the county in which such municipality is situated, if such works and improvements will be of benefit to the municipality providing the same and to the inhabitants thereof.
Any two or more municipalities may jointly erect, construct, and provide such works and improvements within the territorial limits of any municipality joining, or within the territorial limits of some other municipality, and within or without the county in which such municipality or municipalities are situate, and may enter into such arrangements and agreements with the Secretary of Defense, county commissioners, or other public authorities empowered to act in the premises under any law of the United States or of this or any other State, as may be necessary and proper for such purposes, with a view to harmonious and efficient action and proportionate contribution as nearly as may be arrived at or be practicable.
No such works or improvements shall be erected under the provisions of this act in any municipality not joining in the erection or construction thereof, unless such municipality shall first consent thereto.
53 P.S. § 2862