The Department of Natural Resources shall obtain and preserve all obtainable data with reference to the rivers and lakes of Illinois, and make its office a repository thereof, and all such records and data shall be public and available for the use of any person who may be interested therein; and certified copies thereof shall be received in court as evidence of the facts therein set forth. To secure the information authorized by this section to be obtained the Department or its duly authorized agent may cross any lands within the State and enter any building or factory where the power used is of hydraulic generation.
615 ILCS 5/15