From what I understand ice coverage has to less that 250 sq miles or about 3-4 percent of the lake coverage before the boom is removed. I thought there was also a date that they have to start taking it out by, anyone know that date?...............just found this info, interesting
Lake Erie has an average depth of approximately 60 feet (18.2m) Lake Erie will during most winters freeze completely over creating 10,000 square miles (25,900 sq. km) of ice. The Niagara River is only 23 square miles (60 sq. km) and could not handle such a large volume of ice.
With or without the ice boom, only 2% of all ice from Lake Erie enters the Niagara River. The remainder (98%) of the ice pack melts in Lake Erie.
The ice boom does not prevent the ice in Lake Erie from melting any sooner or later. Studies have shown that the ice boom holding back the ice pack on Lake Erie has little effect on the daily weather in Buffalo, New York.
Each Spring, the International Niagara Board of Control determines the date when the ice boom is removed. The decision is based upon the amount of ice remaining in Lake Erie and the weather conditions. Normally, the ice boom has to be removed by April 1st of each year unless there is still more than 250 square miles (650 square kilometres) of ice in the eastern portion of Lake Erie. The earliest removal of the ice boom occurred on March 5th 1998 and the latest removal of the ice boom occurred on April 25th 1997.