Souris River - Misplaced Pages

River in Canada and the United States "Souris Valley" redirects here. For the rural municipality in Saskatchewan, see Rural Municipality of Souris Valley No. 7.

Souris River Mouse River, Rivière Souris
The river in the town of Souris, Manitoba
The Red River drainage basin, with the Souris River highlighted
Location
Countries	Canada United States
Provinces	Manitoba Saskatchewan
State	North Dakota
Cities	Minot, ND Souris, MB Weyburn, SK Melita, MB
Physical characteristics

Source	north of Weyburn
• location	Saskatchewan
• coordinates	49°49′53″N 103°47′46″W / 49.83139°N 103.79611°W / 49.83139; -103.79611

Mouth	Assiniboine River
• location	Manitoba, Canada
• coordinates	49°39′54″N 99°34′07″W / 49.66500°N 99.56861°W / 49.66500; -99.56861
Length	700 km (430 mi)
Basin size	61,000 km (24,000 sq mi)

Discharge
• location	Weyburn, SK; river mile 97.9 (river kilometre 157.6)

Basin features
River system	Red River drainage basin
Tributaries
• left	Antler
• right	Gainsborough

The Souris River (/ˈsʊərɪs/; French: rivière Souris) 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 kilometres (400 mi) in length, it drains about 61,100 square kilometres (23,600 sq mi) 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 kilometres (25 mi) 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 metres (1,120 ft) 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 2,400 acre-feet (3,000,000 m). The Souris Dam was originally built in 1911 and was rebuilt in 1935. The Wawanesa Dam was completed in 1951 storing about 320 acre-feet (390,000 m) 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 3,400 acre-feet (4,200,000 m) in 1937 to 2,100,000 acre-feet (2.6 km) in 1976. It is expected that the total runoff for 2011 at Wawanesa will exceed 3,800,000 acre-feet (4.7 km) 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 cubic feet per second (4.2 m/s) near the border, to about 1,400 cu ft/s (40 m/s) through Melita, to about 1,100 cu ft/s (31 m/s) near Lauder and 1,700 cu ft/s (48 m/s) near Hartney. North of Hartney the capacity increases to more than 3,000 cu ft/s (85 m/s). The drop between the border and Hartney is only about six inches per mile (9.5 cm/km).