Where used in this act singular words shall be construed as including the plural, masculine words shall be construed as including the feminine and neuter, and the following words shall have the following meanings respectively designated for each:

The term “commission” means the Water Supply Commission¹ of Pennsylvania.

The term “dam” means an obstruction, dam, wall, wing wall, wharf, embankment, abutment, projection, or similar analogous structure, or any other obstruction whatever in, along, across, or projecting into any stream or body of water wholly or partly within, or forming part of the boundary of, this Commonwealth, except the tidal waters of the Delaware River and of its navigable tributaries.

The term “dam to develop water power” means a dam for the purpose of developing water power only, or a dam for said purpose and for any other purpose.

The term “dam to supply water for steam power” means a dam for the main purpose of storing, cooling, diverting, and using, or any of them, water for steam raising or steam condensation, or both, in the generation of electric energy for use in public service, which is not a dam to develop water power as hereinbefore defined.

The term “water supply dam” means a dam for the purpose of supplying water, which is not a dam to develop water power nor a dam to supply water for steam power as hereinbefore defined.

The term “power dam” includes dams to develop water power and dams to supply water for steam power.

The term “change in stream to develop water power” means any change in or diminution of the course, current, or cross-section of any stream or body of water for the sole purpose of developing water power, or for said purpose and any other purpose, whether the dam or other means effecting the change be within or without the Commonwealth of Pennsylvania.

The term “change in stream to supply water for steam power” means any such change or diminution for the main purpose of storing, cooling, diverting, and using, or any of them, water for steam raising or steam condensation, or both, in the generation of electric energy for use in public service, which is not a change in stream to develop water power as hereinbefore defined, whether the dam or other means effecting the change be within or without the Commonwealth of Pennsylvania.

The term “change in stream for water supply” means any such change or diminution for the purpose of supplying water, which is not a change in stream to develop water power, nor a change in stream to supply water for steam power, as hereinbefore defined, whether the dam or other means effecting the change be within or without the Commonwealth of Pennsylvania.

The term “change in stream to develop power” includes changes in stream to develop water power and changes in stream to supply water for steam power.

The term “limited power permit” means a permit for a power dam or for a change in stream to develop power, or both, granted under this act.

The term “limited water supply permit” means a permit for a water supply dam or for a change in stream for water supply, or both, granted under this act.

The term “power project” means a complete unit of improvement or development for the supply of water power, or for the procuring or supply, or both, of light, heat, and power, or any of them, by electricity, consisting of a power dam or change in stream to develop power, or both, for which a limited power permit at any time is being sought or has been granted, a power house, water conduits, all dams and appurtenant works which are a part of said unit, and all storage, diverting, or forebay reservoirs directly connected therewith, the primary line or lines transmitting power from the power house to the point of junction with the distribution system or with an interconnected primary transmission system, all miscellaneous structures used and useful in connection with such unit, or any part thereof, and all water rights, rights of way, ditches, dams, reservoirs, lands or interest in lands, the use and occupancy of which are necessary or appropriate in the construction, maintenance, and operation of such unit.

The term “water supply project” means a complete unit of improvement or development for the procuring or supply, or both, of water, which is not a power project as hereinbefore defined, consisting of a water supply dam or change in stream for water supply, or both, for which a limited water supply permit at any time is being sought or has been granted, a reservoir, the dam and other works appurtenant thereto, and all primary water conduits leading immediately therefrom to the point of junction with the distribution system or with an interconnected primary water conduit, and all water rights, rights of way, ditches, dams, reservoirs, and lands or interests in lands, the use and occupancy of which is necessary or appropriate in the construction, maintenance, and operation of such unit.

The term “permittee” means the holder of a limited power permit or a limited water supply permit, and his heirs, successors, and assigns.

The term “navigable waters of the United States” means those parts of streams or other bodies of water over which Congress has jurisdiction under its authority to regulate commerce with foreign nations and among the several States, and which, either in their natural or improved conditions, notwithstanding interruptions between the navigable parts of such streams or waters by falls, shallows, or rapids, compelling land carriage, are used, or suitable for use, for the transportation of persons or property in interstate or foreign commerce, including therein all such interrupting falls, shallows, or rapids, together with such other parts of streams as shall have been authorized by Congress for improvement by the United States, or shall have been recommended to Congress for such improvement after investigation under its authority.