Flooding caused by the Red River's steady rise has forced Canadian Pacific Railway to reroute trains on one Manitoba branch line and to close another, while Canadian National Railway has closed a secondary line.

The Manitoba government was building dikes Wednesday across two of CP's lines to protect the towns of Emerson and Morris against flooding from the Red River and its tributaries, CP spokesman Mike LoVecchio said.

The two lines connect Winnipeg with Morden, Man., and with Glenwood, Minn. Detours are in place for the Winnipeg-Glenwood line, and will result in some service delays, LoVecchio said.

Both outages are typical of flood years and CP planned for them in advance, LoVecchio said.

CN closed its secondary line between Winnipeg and North Dakota on Tuesday night to allow for building of the dike at Morris, said spokesman Warren Chandler.

CN normally operates one train per day in each direction on that line, he said. Flooding has not affected CN's Prairie main lines.

Southern Manitoba rail lines are important movers of Western Canada's grain, but movement usually slows during the spring. The Canadian Wheat Board has already moved crops out of vulnerable areas.

Flooding has also forced BNSF Railway Co., the main freight carrier in North Dakota, to close branch and secondary lines. As of Tuesday, three of its lines in the state were closed, according to the railway's website.