PROJECT ALERT NOTICE (MT WY) Flooding intensifies in northeastern Montana

Date: Mon, 25 Mar 2019 12:01:17 EDT

Summary: Minor to major flooding from snowmelt-runoff and ice-jams continues in eastern Montana.

Gage-heights at nine (9) U.S. Geological Survey streamgages in eastern Montana are exceeding National Weather Service (NWS) minor to major flood stages. Lowland snowmelt-runoff and ice-jams are the cause of most of the flooding. Previously reported flooding in the Milk River basin and tributaries will continue to intensify through the week according to NWS forecasts, with one tributary streamgage currently exceeding major flood stage. Flooding continues along the Little Bighorn River in southeastern Montana where about 50 miles of Interstate 90 from Hardin, Montana to the Wyoming-Montana state line remain closed.

In northeastern Wyoming, NWS reporting Keyhole Reservoir (Belle Fourche River basin) to be 0.05 ft below record levels (20190325 0915 4,100.35 ft).

One streamgage on the Yellowstone River has been damaged and will be repaired today. Three crews of two hydrographers will be completing high-flow measurements today. Closure of I-90 will complicate access to streamgages. Annual exceedance probabilities have not been determined as streamflows are expected to increase at some streamgages.

Cooperators, stakeholders, and the general public are being kept informed by multiple methods including NWSChat, telephone conversations, e-mail, and social media. Photographs of hydrographers measuring flood- and high-flows with text for context and links to data are being posted at Twitter and Instagram accounts @USGS_WY and @USGS_MT.


Interactive flood map for Milk River