The Nelson River, 644 km long, flows north northeast out of Playgreen Lake, at the northwest tip of Lake Winnipeg. It spills out into a number of lakes, including Cross, Sipiwesk, Split and Stevens, flowing east from the latter into Hudson Bay. Its main tributaries are the Burntwood River, on which THOMPSON
, Manitoba, is located, and the Grass River. Sir Thomas BUTTON
wintered at its mouth 1612 and named it for Robert Nelson, a ship's master who died there. The entrance to the river became the scene of a bitter struggle for the fur trade, and YORK FACTORY
was established at Marsh Point, a peninsula separating the Nelson and HAYES RIVER
. However, the Hayes, not the Nelson, became the main route inland. The Nelson takes an often turbulent course through the granitic SHIELD
; as the last link in the long SASKATCHEWAN RIVER
system and as a conduit for the waters of the Red and Winnipeg rivers as well, it has a mean flow at its outlet of 2066 m3
/s. Today the Nelson's drop and huge volume are exploited for hydroelectric power. The largest developments are Kettle Rapids, built 1970-74 (1272 MW), Long Spruce, built 1977-79 (980 MW), and Kelsey, built 1960-72 (224 MW), to provide power for nickel smelters at Thompson.