<P> A useful website hosts measurements of wind, water levels and water temperatures . A real - time interactive map of Seaway Locks, Vessels and Ports is available at . The NOAA - funded Great Lakes Water Level Dashboard compiles statistics on water depth at various points along the Seaway . </P> <P> To create a navigable channel through the Long Sault rapids and to allow hydroelectric stations to be established immediately upriver from Cornwall, Ontario and Massena, New York, Lake St. Lawrence was created behind a dam . It required the condemnation and acquisition by the government of all the properties of six villages and three hamlets in Ontario; these are now collectively known as "The Lost Villages". The area was flooded on July 1, 1958, creating the lake . There was also inundation on the New York side of the border and the village of Louisville Landing was submerged . A notable adverse environmental effect of the operation of the Seaway has been the introduction of numerous invasive species of aquatic animals into the Great Lakes Basin . The zebra mussel has been most damaging in the Great Lakes and through its invasion of related rivers, waterways and city water facilities . </P> <P> The Seaway, along with the Saint Lawrence River it passes through also provides opportunities for outdoor recreation, such as boating, camping, fishing, and scuba diving . Unfortunately invasive species and artificial water level controls imposed by the Seaway have had a negative impact on recreational fishing . Of note, The Old Power House near Lock 23 (near Morrisburg, Ontario) became an attractive site for scuba divers . The submerged stone building has become covered with barnacles and is home to an abundance of underwater life . </P> <P> The Seaway passes through the Saint Lawrence River, which provides a number of divable shipwrecks within recreational scuba limits (shallower than 130 ft (40 m)) The region also offers technical diving with some wrecks lying at 240 ft (73 m). Surprisingly, the water temperature can be as warm as 75 ° F (24 ° C) during the mid to late summer months . The first 10 ft (3 m) of Lake Ontario is warmed and enters the St. Lawrence river as the fast - moving water body has no thermocline circulation . </P>

The st. lawrence seaway has been called canada’s highway to the sea because