Flood in Mercer County, North Dakota

Upwards of nine inches of rain in parts of western Mercer County led to very significant overland flooding. There was also flooding along the Knife River, Spring Creek, and their tributaries. Water was added to the Knife River system not only from rain in Mercer County but rain in Dunn County as well. There was significant damage to roads and crops. Officials estimated damage to at least 90 residences. Damage occurred to storm sewer and sanitary sewer systems. A county emergency declaration was issued.

Several waves of heavy rain, with embedded non severe thunderstorms with torrential rain, moved through western and central North Dakota. There was overland, stream, river and flash flooding, mainly over the southern half of the western and central parts of the state. The hardest hit areas were between Williston and Dickinson, and between Bismarck and Jamestown. Up to six inches of rain fell from Kintyre to Napoleon to Menoken. Up to 11 inches was indicated by radar and verified through ground truth rain gauge reports in the Dunn and Mercer County areas. 10.50 inches of rain was reported nine miles south of Dunn Center, Dunn County. Damage was in the millions of dollars. Some counties had to close roads because of flooding. Weight limits were placed on other roads as the road beds softened. The rain was the result of a mid level atmospheric circulation that moved very slowly across North Dakota. Flood watches were posted for parts of the area more than a day in advance and were followed by advisories and warnings. Several counties issued disaster declarations.