The treaty allows higher summertime diversion at night when tourists are fewer and during the winter months when there are even fewer tourists.[70] This treaty, designed to ensure an "unbroken curtain of water" flowing over the falls, states that during daylight time during the tourist season (April 1 to October 31) there must be 100,000 cubic feet per second (2,800 m3/s) of water flowing over the falls, and during the night and off-tourist season there must be 50,000 cubic feet per second (1,400 m3/s) of water flowing over the falls. This treaty is monitored by the International Niagara Board of Control, using a NOAA gauging station above the falls. During winter, the Power Authority of New York works with Ontario Power Generation to prevent ice on the Niagara River from interfering with power production or causing flooding of shoreline property.