A Century of Streamgaging on the Souris River at Minot, North Dakota

The Souris River — the Mouse River in the U.S. — rises in the Yellow Grass Marshes north of Weyburn, Saskatchewan, flows southeast into North Dakota west of Sherwood, loops, and heads back north into Manitoba near Westhope, joining the Assiniboine River near Brandon.

The U.S. Geological Survey (USGS), with the North Dakota State Water Commission, began measuring it in and near Minot in April 1903, to understand the state's water resources. Today (2016) the gages matter for water supply and for flood monitoring and forecasting. Data have come from five gage locations.

The Anne Street viaduct, where the gage moved in 1909, photographed between 1900 and 1915. State Historical Society of North Dakota.

How gage height was measured

• Before October 1934: local residents read a staff gage, chain gage or wire-weight gage once or twice a day.
• October 1934 to June 2016: strip-chart and then digital recorders driven by a float in a concrete stilling well, which shields the float from wind and turbulence — generally the most accurate method. Strip charts recorded continuously; digital recorders every 15 or 60 minutes.
• Daily gage height is the mean over 24 hours. Before October 1, 2000, daily gage heights were mostly unpublished, though used to compute daily flow. Archived records for four of the five gages, from as early as April 1903 through September 30, 2000, are now in the USGS National Water Information System.

Early methods: (A) staff gage, (B) chain gage, (C) wire-weight gage. USGS.

A stilling-well gage. From Sauer and Turnipseed (2010). USGS.

A mechanical strip-chart recorder. USGS.

Five gages

To get the water-surface elevation, add the gage height to the gage's datum — an arbitrary zero set just below the stream bottom.

• Site 1 began on May 5, 1903, on a footbridge near the Great Northern Railroad roundhouse, east of today's Broadway Bridge. In 1909 it moved a few hundred feet downstream to the Anne Street footbridge (now the Main Street footbridge), same datum. USGS stopped in March 1924, returned in October 1929, and stopped again in September 1934.
• Site 2: the North Dakota State Engineer kept records at the Valker Bridge (now 8th Avenue Southeast), with a different datum.
• Site 3: the State Engineer ran a gage at Saugstad Bridge (now 37th Avenue Southeast), 5 miles southeast of Minot.
• Site 4: in October 1934 USGS built a stilling-well gage with continuous recording about 3.5 miles west of Minot, below the County Road 17 bridge — in use ever since.
• Site 5: a temporary wire-weight gage with a recorder at Broadway Bridge during the record 2011 flood, run until October 2013. Its 15-digit number was replaced by an 8-digit one in April 2016.

Discharge (streamflow)

• 1903–1934: measured in Minot, from bridges or by wading near site 1 or 2. Loaded into NWIS in spring 2016, under site 1's number.
• Since October 1934: measured near site 4, upstream of Minot.
• 2011–13: 16 measurements at Broadway Bridge.
• All daily discharges from 1903 onward are filed under site 4 (05117500), since discharge is comparable at every location except in extreme low flow.

Floods

The Souris floods mostly in spring, from snowmelt plus rain. Its wide, flat valley and gentle slope make it slow to respond, so floods and ponding linger; summer thunderstorms can bring flash floods.

• 1881 or 1882: locals quoted in the April 20, 1904, Minot Daily Optic described a flood at least 3 feet above the 1904 crest. Weather records suggest it was really 1882; no definitive records exist.
• April 20, 1904: 12,000 cubic feet per second (ft³/s).
• June 25, 2011: 27,500 ft³/s, measured at Broadway Bridge (site 4 recorded a peak of 26,900 ft³/s).

The Souris River near the site 4 gage, looking south, June 24, 2011. USGS.

Highest crests at Broadway Bridge (feet above NAVD 88):

Annual peak streamflow at site 4, with lines marking changes of gage location. USGS.

Sources

Based on History of U.S. Geological Survey Streamgaging on the Souris River in and near Minot, North Dakota, 1903–2016, by Kevin K. Baker and Steven M. Robinson, U.S. Geological Survey Fact Sheet 2016–3061 (DOI; publication page). The end of its text, both tables and the figures are restored from the fact sheet's PDF; the Anne Street photograph, from before 1929, is in the public domain. Its location map, on a licensed commercial basemap, is left out. A work of the United States government in the public domain.