As used in this chapter:
(a) “Dam” includes all artificial obstructions.
(b) “Conduit” includes pipe, millrace, ditch, flume, siphon, tunnel, canal, and any other conduit or diversion used for the purpose of taking or receiving water from any river, creek, stream, or lake.
(c) “Owner” includes the United States (except that for the purpose of Sections 5901, 5931, 5933, and 5938, “owner” does not include the United States as to any dam in the condition the dam existed on September 15, 1945), the State, a person, political subdivision, or district (other than a fish and game district) owning, controlling or operating a dam or pipe.
(d) “United States” means the United States of America, and in relation to any particular matter includes the officers, agents, employees, agencies, or instrumentalities authorized to act in relation thereto.