[Code of Federal Regulations] [Title 33, Volume 3] [Revised as of July 1, 2007] From the U.S. Government Printing Office via GPO Access [CITE: 33CFR207.425] [Page 73-74] TITLE 33--NAVIGATION AND NAVIGABLE WATERS CHAPTER II--CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE PART 207_NAVIGATION REGULATIONS--Table of Contents Sec. 207.425 Calumet River, Ill.; Thomas J. O'Brien Lock and Controlling Works and the use, administration and navigation of the lock. (a) Controlling Works. (1) The controlling works shall be so operated that the water level at the downstream end of the lock will be maintained at a level lower than that of Lake Michigan, except in times of excessive storm [[Page 74]] run-off into the Illinois Waterway, or when the lake level is below minus 2 feet, Chicago City Datum. (2) The elevation to be maintained at the downstream end of the lock shall at no time be higher than minus 0.5 feet, Chicago City Datum, and at no time lower than minus 2.0 feet, Chicago City Datum, except as noted in paragraph (a)(1) of this section. (b) Lock--(1) Operation. The Thomas J. O'Brien Lock and Dam is part of the Illinois Waterway which is a tributary of the Mississippi River. All rules and regulations defined in Sec. 207.300, Ohio River, Mississippi River above Cairo, Illinois, and their tributaries; use, administration and navigation shall apply. [40 FR 57358, Dec. 9, 1975]