Floods on the Red River of the North occurred in the context of unusual conditions that
led to serious flooding throughout much of the upper Midwest. Beginning in the fall months
in 1996, much of the region received substantial precipitation in late October and
November. For many areas, this amounted to 4 or more inches above normal. Much of the
precipitation occurred as rainfall during October and early November. The soil profile was
generally wet to 5 feet even though it was a dry summer; the rains that occurred during
November were very efficient in increasing the soil moisture since most, if not all, the
rain that fell was absorbed by the soil. Following the wet fall, the north-central U.S.
experienced horrific conditions over the winter of 1996-97. Blizzard after blizzard during
the second half of November through January built up an enormous snowpack; many areas had
more than 100 inches of snowfall. These amounts were as much as 2-3 times the normal
annual snowfall. Although February and March were quite dry, frigid conditions throughout
much of the winter ensured that as much as 10 inches of snow water equivalent remained on
the ground at the start of the spring melt period.
Early March brought below normal temperatures, delaying the onset of snowmelt. By
mid-March, the snow line had moved north to the vicinity of the northern Iowa state line.
Mid-March saw significant rises and ice jams on the Redwood and Cottonwood Rivers in
Minnesota. Additionally, the Blue Earth and Le Seur Rivers began rising, resulting in
flood stage being reached on the Minnesota River at Mankato. As this flow from the
tributaries of the Minnesota River continued, the Minnesota River rose above flood stage
at all gaging locations.
Significant melt of the deep snow cover started with particularly warm conditions at
the end of March and into early April. At this time, many rivers in South Dakota, southern
Minnesota, and southern North Dakota were rising, in some cases well above flood stage.
Conditions changed dramatically over the weekend of April 5-6, with heavy rain in the
areas already experiencing melt, followed by more blizzard conditions that brought a foot
or more of snow to the northern portions of the Red River of the North Basin in the U.S.
This event increased the amount of water destined to flow into rivers by 2-3 inches and
all but cut off melt due to temperatures dropping well below freezing; the second week in
April saw temperatures that averaged as much as 20 degrees below normal. The cold
temperatures effectively halted snowmelt runoff, with shallow and/or slowly moving water
freezing rapidly--in some cases, seizing anything that remained, including cars and some
livestock. However, the cold did not halt flood flows already moving through rivers in
southern Minnesota, eastern South Dakota, and southeastern North Dakota. In addition to
the havoc wrought by the snow and cold on transportation and, in some cases, on power
distribution, sandbagging became extremely difficult. The reduced runoff and freezing as
well as the added snow water equivalent significantly complicated the forecast problem.
While temperatures moderated in mid-April, they continued below normal until April 17 when
they rose rapidly to above normal with no overnight low temperatures below freezing.
Within a week after the early April blizzard, melt resumed, with additional rises on most
of the area's rivers and streams. Some of the most serious flooding in the U.S. occurred
in the Red River of the North Basin within North Dakota and Minnesota--the area of
coverage of this report. (Serious flooding also occurred in nearby areas of southern
Minnesota, particularly on the Minnesota River, on the James River in eastern South
Dakota, and on portions of the Mississippi River.)
Flooding on the Red River of the North in 1997 established (twentieth century) records
at most locations and was particularly devastating in the towns of Grand Forks, North
Dakota, and East Grand Forks, Minnesota. The summary below provides
a comparison of differences in the new flood records with previous floods of record (from
the twentieth century). With the exception of Grand Forks, which exceeded the previous
(1979) record by over 5 feet, observed crests at forecast locations on the Red River of
the North were within approximately 2 feet of the previous records. Estimated damages for
the complete event, including all United States portions of the Red River of the North,
totaled approximately $4 billion, of which $3.6 billion occurred in the immediate vicinity
of Grand Forks / East Grand Forks. No deaths directly attributable to the flooding
resulted from this event.
Table 1. Red River of the North Flood of
of flood of record and 1997 crest
|East Grand Forks, MN
* Wahpeton, North Dakota, at the southern end of the Red River of
the North, established a new record on April 6, then another crest at or above this on
April 15; the high water mark from these two crests is 19.44 feet.