PROJECT ALERT NOTICE (MT) Flooding in Montana, Day 10

Date: Tue, 21 Jun 2022 23:39:12 EDT

Summary: Flooding persists in the Yellowstone River basin, and now flooding in the Flathead basin, day 10

Flooding persists in the Yellowstone River basin as a secondary peak due to snowmelt runoff over the weekend (June 19-20), and now the Flathead River Basin in Montana is responding to sustained rain in the Flathead Valley coupled with a late snowmelt runoff. Many of the tributaries experienced a secondary peak in the Yellowstone River basin. Gages in the upper portion the Yellowstone River basin have already peaked from this event. The gages on the lower portion of the Yellowstone River continue to rise and are expected to peak by the end of the week and over the weekend. Gages in the upper portion of the Flathead River basin are expected to peak today and into tomorrow. Gages in the lower portion of the Flathead River basin and the lower Clark Fork are expected to peak later in the week.

Yellowstone River Fish Bypass Channel near Intake, MT remains the only gage not operating, and will be reinstalled tomorrow. The WSC has no immediate needs with instrumentation.

Notably, the WY-MT WSC is looking for experience outside the center with assistance in computing indirect measurements of peak flow. A scope of work and budget has been drafted, to include flagging high-water marks in three communities. High-water marks have been flagged at 8 active stations to enable determination of peak flow for this event. High-water marks will be flagged at 4 additional active stations to determine peak flow. High-water marks have been surveyed at two (of the 8) sites. High-water marks for this event will be populated in the Flood Event Viewer. (https://stn.wim.usgs.gov/FEV/). The Montana Department of Natural Resources and Conservation (MT DNRC) is funding $50k toward indirect measurements and high-water marks at discontinued sites. The field work has been completed at Livingston; covered by the DNRC agreement. The remainder will be under the FEMA PSMA.

Currently WY-MT has 7 crews in the field making measurements and field observations around Wyoming and Montana. Crews are downloading measurements, applying shifts and/or extending ratings from the field. The USGS is communicating with the NWS and other cooperators as needed.

WY-MT crews will continue to make measurements through Friday June 24 and will reassess as the weekend approaches.

Please contact Scott Whiteman or Cheryl Miller for questions regarding WY-MT gages.