Any city owning and operating a water works system is hereby authorized and empowered to enter, by any of its employés, upon private lands through which may pass any stream or streams of water supplying such city, for the purpose of patrolling the drainage area of such stream or streams, and making investigations or inquiries pertaining to the condition of the stream or streams, sanitary or otherwise: Provided, however, That any injury or damage done to the property, so entered upon, shall be paid by such city.
53 P.S. § 2901