PROJECT ALERT NOTICE (ND SD) Dakota WSC Flooding

Date: Fri, 05 Apr 2019 17:02:40 EDT

Summary: USGS response to flooding in SD & ND (Day 23).

Gage-heights at forty-four (44) U.S. Geological Survey streamgages in South Dakota (SD) and North Dakota (ND) are exceeding National Weather Service (NWS) minor to major flood stages. The distribution of the forty-four sites experiencing flooding in the Dakotas 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 into the weekend," per NWS in Grand Forks, ND today. The James River in ND south of I-94 has peaked for now, but that flow will soon impact SD stations. 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). USGS crews are finding shifts from +2.25 to -4.0 ft. as of 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 did just measure a +2.25 ft. shift at Fargo which may impact the peak forecast. 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 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). Breakout flow from the Elm River into Moccasin Creek is occurring. Moccasin Creek flows through Aberdeen, SD with the potential for flooded property if significant breakout flow from the Elm were to enter Moccasin Creek. The USGS has contacted local officials offering assistance. Eight of nine sites on the James River in SD are at major flood stage with the remaining one at moderate. Crests are currently near Aberdeen, SD and will move downstream over the next week. In the Big Sioux Basin flows are receding with most stations at minor flood stage.

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 343 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. All data section staff in both states are deployed today to measure flows and repair gages. Five crews (11 staff) will be deployed 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 today (https://www.usgs.gov/news/media-advisory-usgs-crews-measure-record-flooding-fargo). Two staff from the Office of Communications - Central States will be on site this weekend in Fargo, ND. Stakeholders are being informed of our activities through updates to NWISWeb, NWSChat, email, and phone calls.

Dakota WSC Flood Map
USGS Red River Stations