<Tr> <Td> </Td> <Td> This article's factual accuracy is disputed . Relevant discussion may be found on the talk page . Please help to ensure that disputed statements are reliably sourced . (September 2017) (Learn how and when to remove this template message) </Td> </Tr> <Table> <Tr> <Td_colspan="2"> Saint Lawrence River </Td> </Tr> <Tr> <Td_colspan="2"> Fleuve Saint - Laurent, Fleuve St - Laurent, St - Lawrence River, St - Laurent River </Td> </Tr> <Tr> <Td_colspan="2"> Saint Lawrence River near Alexandria Bay </Td> </Tr> <Tr> <Td_colspan="2"> Name origin: Saint Lawrence of Rome </Td> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> <Tr> <Th> Countries </Th> <Td> Canada, United States </Td> </Tr> <Tr> <Th> Provinces </Th> <Td> Ontario, Quebec </Td> </Tr> <Tr> <Th> State </Th> <Td> New York </Td> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> <Tr> <Th> Source </Th> <Td> Lake Ontario </Td> </Tr> <Tr> <Td> - location </Td> <Td> Kingston, Ontario / Cape Vincent, New York </Td> </Tr> <Tr> <Td> - elevation </Td> <Td> 74.7 m (245 ft) </Td> </Tr> <Tr> <Td> - coordinates </Td> <Td> 44 ° 06 ′ N 76 ° 24 ′ W ﻿ / ﻿ 44.100 ° N 76.400 ° W ﻿ / 44.100; - 76.400 </Td> </Tr> <Tr> <Th> Mouth </Th> <Td> Gulf of St. Lawrence / Atlantic Ocean </Td> </Tr> <Tr> <Td> - elevation </Td> <Td> 0 m (0 ft) </Td> </Tr> <Tr> <Td> - coordinates </Td> <Td> 49 ° 30 ′ N 64 ° 30 ′ W ﻿ / ﻿ 49.500 ° N 64.500 ° W ﻿ / 49.500; - 64.500 Coordinates: 49 ° 30 ′ N 64 ° 30 ′ W ﻿ / ﻿ 49.500 ° N 64.500 ° W ﻿ / 49.500; - 64.500 </Td> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> <Tr> <Th> Length </Th> <Td> 500 km (310 mi) Excluding the estuary . Ca . 1200 km if included . </Td> </Tr> <Tr> <Th> Basin </Th> <Td> 1,344,200 km (519,000 sq mi) </Td> </Tr> <Tr> <Th> Discharge </Th> <Td> for below the Saguenay River </Td> </Tr> <Tr> <Td> - average </Td> <Td> 16,800 m / s (590,000 cu ft / s) </Td> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> <Tr> <Td_colspan="2"> Map of the Saint Lawrence / Great Lakes Watershed </Td> </Tr> </Table> <Tr> <Td_colspan="2"> Saint Lawrence River </Td> </Tr> <Tr> <Td_colspan="2"> Fleuve Saint - Laurent, Fleuve St - Laurent, St - Lawrence River, St - Laurent River </Td> </Tr>

When does the st. lawrence became salt water