Chad White, age 11, of Burlington, Vt., for his question:
HOW LONG IS THE SAINT LAWRENCE RIVER?
The Saint Lawrence River is the largest river in Canada and one of the largest rivers in the world. The river proper from Lake Ontario to its mouth in the Gulf of Saint Lawrence is 710 miles long. But the greater Saint Lawrence River from the head of its most distant source, the Saint Louis River, to the Gulf is about 1,900 miles long.
The Saint Lawrence begins at the northeast end of Lake Ontario and flows northeast until it enters the Gulf of Saint Lawrence. But the source of this vast system is the Saint Louis River, which rises in northeastern Minnesota and enters into Lake Superior at Duluth.
Then the Saint Mary's River connects Lake Superior to Lake Huron. Next in line the Saint Clair and Detroit rivers connect Lake Huron and Lake Erie. Finally, the Niagara River with its great falls and rapids connects Lake Erie and Lake Ontario.
Many smaller streams empty into the Saint Lawrence. They include the Ottawa River, which enters from the north at the island of Montreal.
The Saint Lawrence has an average width of one and a quarter miles as it flows from Lake Ontario to Quebec. In some places, the great river narrows to less than one mile, but in others it expands to form "lakes."
The most famous of the river lakes are Lake Saint Francis, a 30 mile long stretch of water above Montreal, and Lake Saint Peter, 28 miles long, which is located halfway between Montreal and Quebec.
The channel of the Saint Lawrence slowly broadens below Quebec to form the great estuary that actually blends with the Gulf of Saint Lawrence at Anticosti Island.
Below the Isle d'Orleans, the channel of the river is never less than 10 miles wide. The river is 25 miles wide where the Saguenay empties into it, and opposite Gaspe, it is 90 miles wide.
The Saint Lawrence River drops 245 feet between Lake Ontario and the city of Quebec. Most of this fall is above the city of Montreal.
There are 30 miles of rapids between Lake Ontario and Montreal.
The tide goes up the Saint Lawrence River as far as the Saint Maurice River, at Trois Rivieres. There, the water may rise as high as 19 feet. The rise at Quebec is nearly as great.
Bad floods on the Saint Lawrence River are unknown because the waters of the Great Lakes do not rise and fall suddenly. Mud and silt that flow into the Great Lakes settle to the bottom, leaving the Saint Lawrence clean. However, it has recently been polluted by sewage, industry and ship wastes.
Low water levels and pollution have caused many problems along the Saint Lawrence. But studies are conducted regularly and problems are being solved.
Authorities say that the Saint Lawrence River is second only to the Amazon in the amount of water it pours into the ocean every day. It drains over 500,000 square miles, including the Great Lakes and southeastern Canada.