Mississippi River, Twin City Locks and Dam, St. Paul and Minneapolis, Minn.; pool level.
In accordance with the provisions of Article 8 of Federal Power Commission License of June 7, 1923 (Project No. 362-Minn., Ford Motor Co.), this section is prescribed for the control of the pool level created by the Twin City Locks and Dam, Minneapolis, in the interest of navigation, and supersedes rules and regulations made effective January 1, 1928, by the Secretary of War:
The pool above the dam shall not be allowed to drop below elevation 744.5 (Cairo datum), except after loss or lowering of flashboards and before replacement or raising of same, during the navigation season; nor below elevation 743.3 during the period when the river is closed to navigation. The variation of pool level shall not exceed 0.5 foot per day whenever the pool is below elevation 745.5, and in addition, during the period when the river is closed to navigation, the maximum rate of such variation shall not exceed 0.1 foot per hour; except that during the navigation season, increases in pool level at rates greater than that specified may be made to eliminate wasting of water during an increase in river flow.
Whenever, due to high flows, the pool above the dam is above elevation 746.5, all flashboards on the crest of the dam shall be removed or in the lowered position.
To protect navigation in cases of emergency, such as the stranding of a boat or the loss of a pool below the Twin City Dam, etc., the licensee shall temporarily discharge water at such rates, subject to the limitations of paragraph (a) of this section, as may be directed by the U.S. District Engineer in charge of the locality.
It shall be the duty of the U.S. District Engineer in charge of the locality to notify the licensee of the periods during which the river shall be considered open to navigation.
It shall be the further duty of the said District Engineer or his authorized agent, by frequent inspections, to determine whether paragraphs (a) to (d) of this section are being observed. In case of noncompliance he shall so notify the licensee and report the facts to the Chief of Engineers.
[Regs., Feb. 24, 1938]