 During the summer months, at least per second of water traverses the falls, some 90% of which goes over the Horseshoe Falls, while the balance is diverted to hydroelectric facilities.This is accomplished by employing a weir – the International Control Dam – with movable gates upstream from the Horseshoe Falls.The falls' flow is further halved at night, and, during the low tourist season in the winter, remains a minimum of per second.