To preserve the scenic spectacle of Niagara Falls, Article IV of the 1950 Treaty specifies that no diversions of water shall be made for power purposes that will reduce the flow over the Falls to less than 100,000 cubic feet per second (cfs) during the Tourist Season daylight hours which are 8:00 a.m. to 10:00 p.m. Eastern Standard Time (E.S.T.) from April 1st through September 15th, and from 8:00 a.m. to 8:00 p.m. E.S.T. from September 16th through October 31st. At all other times, the flow over the Falls shall not be less than 50,000 cubic feet per second. All Treaty water in excess of that reserved for scenic purposes may be diverted for power purposes.