The Souris River or Mouse River (as it is alternatively known in the U.S., a translation of its French name) is a river in central North America. Approximately 700 km in length, it drains about 61100 km2 in Canada and the United States. Rising in southern Saskatchewan in the Yellow Grass Marshes north of Weyburn, the river wanders southeast into the U.S. through North Dakota beyond Minot to its most southern point at Velva, and then back north into Canada in southwestern Manitoba. Flowing east, it passes through the communities of Melita, Hartney, Souris, and Wawanesa, Manitoba, prior to the confluence with the Assiniboine River near Treesbank, about 40 km southeast of Brandon. The main tributaries of the Souris in Manitoba are the Antler River, Gainsborough Creek, and Plum Creek. The elevation at the confluence is approximately 340 m above sea level. At the end of the last ice age, over 10,000 years ago, the rapid draining of former Glacial Lake Regina eroded a large channel that is now occupied by the much smaller contemporary Souris River. Also, much of the drainage basin is fertile silt and clay deposited by another former glacial lake, Lake Souris.

Flow rates and flood potential

During the period from 1930 to 1941 severe drought conditions prevailed and PFRA constructed four stock watering dams. In 1937 the Snyder and Ross Dams were built near Melita. In 1938 the Napinka Dam was built and the Hartney Dam was built in 1941. These were all stop log dams with a total capacity of 2400 acre.ft. The Souris Dam was originally built in 1911 and was rebuilt in 1935. The Wawanesa Dam was completed in 1951 storing about 320 acre.ft of water. Most of the annual flow of the Souris River comes from snow melt and spring rains. The annual flow volume varies dramatically from 3400 acre.ft in 1937 to 2100000 acre.ft in 1976. It is expected that the total runoff for 2011 at Wawanesa will exceed 3800000 acre.ft about a one in 500-year event. The average annual runoff is equivalent to 3 mm over the entire Souris River watershed. Two large dams in Saskatchewan, Rafferty Dam and Grant Devine Dam were built, in part, to reduce flood peaks on the Souris River. In summer 2011, a historic flood affected much of the Souris River basin, overtopping levees and causing the evacuation of about 11,000 residents in Minot as well as significant damage to farmland and other property along the length of the river. The channel capacity of the river in Manitoba varies from about 150 cuft/s near the border, to about 1400 cuft/s through Melita, to about 1100 cuft/s near Lauder and 1700 cuft/s near Hartney. North of Hartney the capacity increases to more than 3000 cuft/s. The drop between the border and Hartney is only about 6 in/mi.

Tributaries

Communities along the river

Cities and towns

Rural Municipalities

Bridges across the river

Fish species

Fish species include walleye, yellow perch, northern pike, white sucker, black bullhead, goldeye, brown bullhead, smallmouth bass, and burbot.