The floods of 1950, 1966, 1979, and 1997 were the largest and most damaging floods that have occurred throughout the RRB since streamflow records began in the early 1880's ( Tables 1 and 2 ). Upstream of the confluence of the Turtle River and Red River, however, the streamflow during the 1997 flood was greater than the streamflow during the 1950, 1966, and 1979 floods, and probably the 1897 flood. The twenty largest recorded floods, listed by flow for selected cities, are listed in Table 3.

The 1826 flood is believed to be the greatest flood in the Red River valley in the last 200 years. The 1826 flood probably was the greatest on many streams in the RRB. From the accounts of the 1826 flood, several conclusions can be can be reached: (1) the fall of 1825 was extremely wet and most of the lakes and wetlands were overflowing, (2) a major snowstorm occurred in late fall, (3) a cold, snowy winter permitted an exceptionally deep snow pack to develop over much of the RRB, and (4) the coldest estimated March-April mean temperature at Winnipeg since 1815, was in 1826.

The flood of 1997 was the worst flooding in more than 100 years. Recurrence intervals for peak flows on the main stem of the Red River ranged from 50 to 500 years ( Table 3 ). On April 6, 1997, the stage of the Red River at Wahpeton, ND, was 19.42 ft., which is 1.47 ft. higher than the record set in 1989. On April 15, 1997, 9 days later, flow was 12,800 cubic feet per second (cfs), and the stage was 19.22 ft. The recurrence interval for the April 15 peak flow was between 100 and 200 years. On April 8, 1997, most of the 1,700 people in Ada, MN, were forced to flee their homes as overland flow from the flooding Marsh and Wild Rice Rivers inundated the town. Freezing temperatures from the late-spring blizzard caused a layer of ice to form over the flooding waters. On April 17, 1997, flow on the Red River at Fargo, ND, and Moorhead, MN, was 28,000ft cfs. The recurrence interval for this peak flow was between 50 and 100 years. On April 18, 1997, the stage was 39.62 ft., which exceeded the record of 39.10 ft. set 100 years earlier. On April 18, 1997, flow on the Red River at Grand Forks, ND, was 136,900 cfs, and the stage was 52.21 ft, which is more than 2 ft higher than the record set in 1897. The recurrence interval for this peak flow was between 200 and 500 years. The stage continued to rise to 54.35 ft on April 22, 1997. On April 25, 1997, flow on the Red River at Drayton, ND, was 123,000 cfs., and the stage was 45.56 ft, which is 1.90 ft higher than the record set in 1979. The recurrence interval for the April 25 peak flow was between 200 and 500 years.

In addition to flow on the main stem, peak flow on many rivers and streams tributary to the Red River had 10-year or greater recurrence intervals during the 1997 floods. The recurrence interval for flow on the Bois de Sioux River near White Rock, SD, was between 200 and 500 years, and the recurrence interval for flow on the Wild Rice River at Twin Valley, MN, was between 100 and 200 years. The recurrence interval for flow on the Red Lake River at Crookston, MN, was between 50 and 100 years. The Red Lake River normally accounts for almost 35 percent of the Red River?s flow (Rowland, 1997).