PROJECT ALERT NOTICE (ND SD) Dakota WSC Flooding

Date: Sun, 07 Apr 2019 16:14:49 EDT

Summary: USGS response to flooding in SD & ND (Day 25).

Gage-heights at forty-eight (48) 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-eight sites experiencing flooding can be observed at the WaterWatch link below.

Eastern ND - Last night brought rain and a few thunderstorms to the region. "Warming temps along with rain has lead to continued widespread overland flooding ... a cool down by mid-week could slow down runoff," per NWS in Grand Forks, ND today. There is also the potential for additional precipitation mid-week from another storm system, but the track is still uncertain. The James River in ND south of I-94 is receding. Sites on the Red and Wild Rice Rivers have peaked south of Fargo, ND. The peak on the Red River at Fargo has been pushed back to April 8 (Monday) at major flood stage of about 35 ft. Streamflow measurements on the Red River at Fargo are being made daily to document the changing shift. Stages are rapidly rising at most sites north of Fargo, ND with some variability in timing caused by the depth of snowpack in each basin (the deeper the snowpack the longer the delay in runoff). Ice is still present at many sites from Fargo, ND to Grand Forks, ND and at almost all sites north of Grand Forks, ND. The Red River at Grand Forks, ND is now expected to reach 48 ft. (major flood stage starts at 46 ft.) by late this week. 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 - The same precipitation that could impact the Red River Basin mid-week will affect most of SD with a potentially significant amount of wintry mix. The Elm and James Rivers near Aberdeen have peaked. Moccasin Creek rose to within less than a foot of peak of record (POR) but has stopped climbing. Local news coverage available at https://www.aberdeennews.com/news/local/moccasin-creek-hits-flood-stage-city-prepares-for-more-water/article_f2913393-a02c-5362-a49f-4f359e8af0f9.html

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 https://waterdata.usgs.gov/nwis/uv?06473000) at some sites. USGS crews have been measuring daily due to the substantial change in flow. Eight of nine sites on the James River in SD will remain at major flood stage this week. In the Big Sioux Basin flows are responding to 0.5 to 1.5 inches of rain yesterday with stage increasing back to moderate flood stage at all sites south of Watertown, SD.

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 383 measurements despite ice and overland flooding challenges. High stages in the shallow gradient of the James, Big Sioux, and Red Rivers is resulting in extensive (miles in some cases) submerged floodplains with road overflow. Eight RDGs deployed in eastern ND are operational. Five field crews and 14 staff in total are working today. 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/

One staff member from the Office of Communications - Central States is deployed with a field crew in Fargo, ND today. Two interviews with local TV media are scheduled for 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