Final answer:
The Saskatchewan River flows eastward across Saskatchewan, eventually emptying into Lake Winnipeg, and features a delta at its mouth. Weirs like the one on the Humber River in Ontario can manage river flows and prevent flooding. The river has ecological and historical significance.
Step-by-step explanation:
The river that flows eastward across Saskatchewan and empties into Lake Winnipeg is the Saskatchewan River. This river system is part of a larger watershed that extends across multiple Canadian provinces. The point where a river empties into a body of water, like the Saskatchewan River into Lake Winnipeg, usually features a delta containing gravel, sand, and silt—materials carried by the river and deposited at its mouth due to the low energy of the water there.
An example can be seen at the mouth of the Yukon River in Alaska. Protective structures such as weirs are sometimes constructed along rivers to manage water flow and prevent issues such as flooding; for instance, a weir was built on the Humber River in Ontario. The Saskatchewan River is significant not only for its role in the ecosystem but also for its historical importance in the development of the region.