PROJECT ALERT NOTICE (ND SD) Dakota WSC Flooding

Date: Sat, 06 Apr 2019 16:14:31 EDT

Summary: USGS response to flooding in SD & ND (Day 24).

Gage-heights at forty-seven (47) U.S. Geological Survey streamgages operated by the Dakota WSC in South Dakota (SD), North Dakota (ND), and Minnesota (MN) are exceeding National Weather Service (NWS) minor to major flood stages. The distribution of the forty-seven sites experiencing flooding can be observed at the WaterWatch link below.

Eastern ND - "Warming temperatures and rain will promote increased snowmelt runoff, overland flow, and potential ice jam flooding this weekend and into early next week," per NWS in Grand Forks, ND today. The James River in ND south of I-94 is receding. In the Red River Basin, river levels are peaking at many sites from Wahpeton, ND to Fargo, ND, are rapidly rising from Fargo, ND to Grand Forks, ND, and are slowly rising north of Grand Forks, ND. Ice is clearing south of Fargo, ND but still causing backwater north of there. As the ice moves out shifts are transitioning from negative (backwater from ice) to positive on the rising limb (shifts will usually trend back to negative after the peak). The shift at the Red River at Fargo, ND changed from a +2.25 ft. yesterday to a +0.91 ft. today. The Red River at Fargo, ND is forecasted to crest April 7 (Sunday) at major flood stage of about 35 ft. (peak of record is 40.84 ft. in 2009). USGS crews will measure the Red River at Fargo again tomorrow to document any change in shift. Links to data and imagery for the Red River Basin are provided below:

USGS installed a webcam at Fargo, ND with real-time imagery available at https://cida.usgs.gov/stormsummary/timelapse/BasicData/DakotaWSC/DWSC/DAK_Red_River_Fargo_timelapse_videos/frame_gallery/

USGS photos from the field are added daily to (DOI access only): https://drive.google.com/drive/folders/1bNiqh_sBAegZgSJQyocSZ2skHDlsJkVf?usp=sharing

Eastern SD - Attention is still focused on the confluence of the James and Elm Rivers near Aberdeen, SD. The Elm River nr Ordway (06471510) did briefly exceed peak of record (POR) stage last night most likely in response to ice jamming. Increased breakout flow from the Elm to Moccasin Creek during the jam could explain the renewed rise on Mocassin Creek today (currently one foot below POR). Moccasin Creek flows through Aberdeen, SD with the potential for causing property flooding. Crews will be measuring flow in the area today. The shallow gradient of the James River in comparison to its tributaries is resulting in backwater and even flow reversals of up to -1800 cfs (see 06471000 or 06473000) at some sites. Eight of nine sites on the James River in SD are at major flood stage with the remaining one at moderate. The Elm River near Aberdeen, SD has peaked with the James near Aberdeen, SD peaking today. In the Big Sioux Basin flows are receding with most stations at minor flood stage. Some stations in the SE corner of SD are responding to overnight precipitation of 0.5 to 1.5 inches. Another quarter inch is expected tonight with higher amounts possible from thunderstorms.

Approximate annual exceedance probabilities (AEP) will be provided for various basins once the peaks have passed.

Since the beginning of flood conditions on March 13, 2019, USGS crews in the DWSC have made 366 measurements despite ice and overland flooding challenges. High stages in the shallow gradient James and Red Rivers is resulting in extensive (miles in some cases) submerged floodplains with road overflow. Eight RDGs deployed in eastern ND are operational. Six field crews and 15 staff in total are working this weekend. Many bubbler lines have been damaged by ice, but non-contact auxiliary sensors are operational at most. Crews are actively documenting high water marks. Two water-quality samples were collected this week.

The Dakota WSC Facebook page has also been updated with recent flood information: https://www.facebook.com/USGSDakotas/

A media advisory was released yesterday (https://www.usgs.gov/news/media-advisory-usgs-crews-measure-record-flooding-fargo). One staff member from the Office of Communications - Central States is deployed with a field crew in Fargo, ND today. Stakeholders are being informed of our activities through updates to NWISWeb, NWSChat, email, and phone calls.

Dakota WSC Flood Map
USGS Red River Stations