ol- NEW YORK STATE MUSEUM 



miles in the province of Ontario. The standard low-water eleva- 

 tion of Lake Ontario is taken as 244.53 feet, and the standard 

 high-water elevation as 249.04 feet above tide. 



St Lawrence river is considered as beginning at Gallops rapids. 



The following tabulation gives the elevation of water surface at a 

 number of points. 1 



Elevation above tide of low-water and high-water surface 

 of St. Lawrence river 



T,™ Q ii*,- Standard low Standard high 



^ ocaJlt > water. water. 



Feet Feet 



Ogdensburg 244.28 248.57 



Lake St Francis, at Valley field 153 . 50 155 . 94 



Lake St Louis, at Melicheville 70.0 77.50 



Montreal 23.10 35.7 



The area of water surface of the St Lawrence from Gallops 

 rapids to Montreal is 220 square miles, and the total area of 

 catchment not included in the surface of the river is 5710 square 

 miles, of which 3S00 square miles lie in New York, 620 in Ontario, 

 and 1290 in Quebec. The total area of the catchment, including 

 water surface of the river, is 5930 square miles. 



The only measurements as to the discharge of St Lawrence river 

 thus far made are those of the Lake Survey, which give a mean 

 discharge of 300.000 cubic feet per second. The recent data would 

 indicate that this figure is somewhat too large, as in the Lake 

 Survey discharge of Niagara river. The streams tributary to Lake 

 Ontario, however, issue from a region of ^heavier rainfall than 

 those tributary to the Upper Great Lakes and, as shown by the 

 runoff tables of this report, are generally much better water 

 yielders. Taking everything into account, it is probable that 

 the minimum discharge of St. Lawrence river will not be less 

 than about 8 to 10 inches per year over the entire catchment area. 

 A runoff of 12 inches per year would give a mean discharge of 

 234,300 cubic feet per second, or a discharge of 0.884 cubic foot 

 per second per square mile. A mean discharge of 300,000 cubic 



l Report of U f S. Deep Waterways Commission, 1897, p. 152. 



