Flooding and High-Flow Conditions in Wyoming and Montana
Greybull River near Basin, Wyoming
June 1963
N F Flathead River at Blankenship Bridge near Columbia Falls, MT
1964
Swiftcurrent Creek at Many Glacier, MT
Nov. 7, 2006 @ 1400 hrs
Wind River near Crowheart, WY
June 15, 2017 @ 13,300 ft3/s
The USGS monitors flood and high-flow conditions at more than 300 streamgages across Montana and Wyoming. Water level and flow information are used by the National Weather Service (NWS) to make accurate flood forecasts. High-flow conditions are expressed as percentiles comparing current (within the past few hours) instantaneous flow to historical daily mean flow for all days of the year.
A percentile is a value on a scale of one hundred that indicates the percent of a distribution that is equal to or below it.
- "<95" indicates that the estimated streamflow is less than the 95th percentile for all days of the year,
- "95-98" indicates that the estimated streamflow is between the 95th and 98th percentiles for all days of the year,
- ">=99" indicates that estimated streamflow is greater than the 99th percentile, and
- "Not ranked" indicates that a flow category has not been computed. Common reasons for a "Not ranked" category are insufficient historical data or no current streamflow estimates.
Flood stages are determined by the NWS; not all USGS streamgages have flood stages. A depiction of other streamgages at or above flood stage is available the NWS River Conditions Map.
Current Flooding and High-Flow Conditions:
(Current-conditions data are provisional and subject to change)
Wyoming:
- Map: Flood and high flows
- Data table: Locations above flood stages
- Map: Current streamflow conditions vs historical streamflows
- Flood of August 1, 1985 in Cheyenne, WY
- Floods of May 1978 in southeastern Montana and northeastern Wyoming
Montana:
- Map: Flood and high flows
- Data table: Locations above flood stages
- Map: Current streamflow conditions vs historical streamflows
- Floods of May 1981 in west-central Montana
- Floods of May 1978 in southeastern Montana and northeastern Wyoming
- Floods of June 1964 in northwestern Montana
How can a 100-year flood strike twice in 15 years? This is a downloadable poster discussing the meaning and use of probability language in flood characterization.
Poster: 100-Year Flood--It's All About Chance
Below are other science projects associated with floods and high-flows in Wyoming and Montana.
Black Hills Area Floods - 1921 to 1930
Black Hills Area Floods - 1961 to 1970
Black Hills Area Floods - 1931 to 1940
Black Hills Area Floods - 1901 to 1910
Black Hills Area Floods - 1941 to 1950
Black Hills Area Floods - 1951 to 1960
Black Hills Area Floods - 1911 to 1920
Black Hills Area Floods - 1971 to 1980
Black Hills Area Floods - 1877 to 1890
Black Hills Area Floods - 1891 to 1900
The 1972 Black Hills-Rapid City Flood
Below are data or web applications associated with floods and high-flows in Wyoming and Montana.
USGS Peak Streamflow Data
The National Water Information System (NWIS) is the USGS water data portal where you can find a wealth of historic and real-time data related to floods. The NWIS website also is where you can query peak streamflow data by station, state (Wyoming or Montana), or region.
FloodWatch - View flood and high-flow conditions.
The USGS FloodWatch website is a map-based resource from USGS WaterWatch that gives users hourly visual updates for flood conditions at over 3000 locations across the United States (Wyoming or Montana). Learn how to use FloodWatch.
Surface-water data for Wyoming
Real-time, daily, peak-flow, field measurements, and statistics of current and historical data that describe stream levels, streamflow (discharge), reservoir and lake levels, surface-water quality, and rainfall in Wyoming. Surface-water data are collected and stored as either discrete field-water-level measurements or as continuous time-series data from automated recorders.
Surface-water data for Montana
Real-time, daily, peak-flow, field measurements, and statistics of current and historical data that describe stream levels, streamflow (discharge), reservoir and lake levels, surface-water quality, and rainfall in Montana. Surface-water data are collected and stored as either discrete field-water-level measurements or as continuous time-series data from automated recorders.
Below are publications associated with floods and high-flows in Wyoming and Montana.
Montana StreamStats
The effects of Missouri River mainstem reservoir system operations on 2011 flooding using a Precipitation-Runoff Modeling System model
1976 Big Thompson flood, Colorado — Thirty years later
1976 Big Thompson flood, Colorado
Summary of significant floods in the United States and Puerto Rico, 1994 through 1998 water years
The world's largest floods, past and present: Their causes and magnitudes
Relations between total-sediment load and peak discharge for rainstorm runoff on five ephemeral streams in Wyoming
Large floods in the United States: where they happen and why
Peak-flow characteristics of Wyoming streams
The 1972 Black Hills-Rapid City Flood Revisited
Using the National Flood Frequency Program, version 3; a computer program for estimating magnitude and frequency of floods for ungaged sites
The National Flood Frequency Program, version 3 : a computer program for estimating magnitude and frequency of floods for ungaged sites
Summary of significant floods in the United States, Puerto Rico, and the Virgin Islands, 1970 through 1989
Below are news stories associated with floods and high-flows in Wyoming and Montana.
Study Links Major Floods in North America and Europe to Multi-Decade Ocean Patterns
The number of major floods in natural rivers across Europe and North America has not increased overall during the past 80 years, a recent study has concluded. Instead researchers found that the occurrence of major flooding in North America and Europe often varies with North Atlantic Ocean temperature patterns.
The USGS monitors flood and high-flow conditions at more than 300 streamgages across Montana and Wyoming. Water level and flow information are used by the National Weather Service (NWS) to make accurate flood forecasts. High-flow conditions are expressed as percentiles comparing current (within the past few hours) instantaneous flow to historical daily mean flow for all days of the year.
A percentile is a value on a scale of one hundred that indicates the percent of a distribution that is equal to or below it.
- "<95" indicates that the estimated streamflow is less than the 95th percentile for all days of the year,
- "95-98" indicates that the estimated streamflow is between the 95th and 98th percentiles for all days of the year,
- ">=99" indicates that estimated streamflow is greater than the 99th percentile, and
- "Not ranked" indicates that a flow category has not been computed. Common reasons for a "Not ranked" category are insufficient historical data or no current streamflow estimates.
Flood stages are determined by the NWS; not all USGS streamgages have flood stages. A depiction of other streamgages at or above flood stage is available the NWS River Conditions Map.
Current Flooding and High-Flow Conditions:
(Current-conditions data are provisional and subject to change)
Wyoming:
- Map: Flood and high flows
- Data table: Locations above flood stages
- Map: Current streamflow conditions vs historical streamflows
- Flood of August 1, 1985 in Cheyenne, WY
- Floods of May 1978 in southeastern Montana and northeastern Wyoming
Montana:
- Map: Flood and high flows
- Data table: Locations above flood stages
- Map: Current streamflow conditions vs historical streamflows
- Floods of May 1981 in west-central Montana
- Floods of May 1978 in southeastern Montana and northeastern Wyoming
- Floods of June 1964 in northwestern Montana
How can a 100-year flood strike twice in 15 years? This is a downloadable poster discussing the meaning and use of probability language in flood characterization.
Poster: 100-Year Flood--It's All About Chance
Below are other science projects associated with floods and high-flows in Wyoming and Montana.
Black Hills Area Floods - 1921 to 1930
Black Hills Area Floods - 1961 to 1970
Black Hills Area Floods - 1931 to 1940
Black Hills Area Floods - 1901 to 1910
Black Hills Area Floods - 1941 to 1950
Black Hills Area Floods - 1951 to 1960
Black Hills Area Floods - 1911 to 1920
Black Hills Area Floods - 1971 to 1980
Black Hills Area Floods - 1877 to 1890
Black Hills Area Floods - 1891 to 1900
The 1972 Black Hills-Rapid City Flood
Below are data or web applications associated with floods and high-flows in Wyoming and Montana.
USGS Peak Streamflow Data
The National Water Information System (NWIS) is the USGS water data portal where you can find a wealth of historic and real-time data related to floods. The NWIS website also is where you can query peak streamflow data by station, state (Wyoming or Montana), or region.
FloodWatch - View flood and high-flow conditions.
The USGS FloodWatch website is a map-based resource from USGS WaterWatch that gives users hourly visual updates for flood conditions at over 3000 locations across the United States (Wyoming or Montana). Learn how to use FloodWatch.
Surface-water data for Wyoming
Real-time, daily, peak-flow, field measurements, and statistics of current and historical data that describe stream levels, streamflow (discharge), reservoir and lake levels, surface-water quality, and rainfall in Wyoming. Surface-water data are collected and stored as either discrete field-water-level measurements or as continuous time-series data from automated recorders.
Surface-water data for Montana
Real-time, daily, peak-flow, field measurements, and statistics of current and historical data that describe stream levels, streamflow (discharge), reservoir and lake levels, surface-water quality, and rainfall in Montana. Surface-water data are collected and stored as either discrete field-water-level measurements or as continuous time-series data from automated recorders.
Below are publications associated with floods and high-flows in Wyoming and Montana.
Montana StreamStats
The effects of Missouri River mainstem reservoir system operations on 2011 flooding using a Precipitation-Runoff Modeling System model
1976 Big Thompson flood, Colorado — Thirty years later
1976 Big Thompson flood, Colorado
Summary of significant floods in the United States and Puerto Rico, 1994 through 1998 water years
The world's largest floods, past and present: Their causes and magnitudes
Relations between total-sediment load and peak discharge for rainstorm runoff on five ephemeral streams in Wyoming
Large floods in the United States: where they happen and why
Peak-flow characteristics of Wyoming streams
The 1972 Black Hills-Rapid City Flood Revisited
Using the National Flood Frequency Program, version 3; a computer program for estimating magnitude and frequency of floods for ungaged sites
The National Flood Frequency Program, version 3 : a computer program for estimating magnitude and frequency of floods for ungaged sites
Summary of significant floods in the United States, Puerto Rico, and the Virgin Islands, 1970 through 1989
Below are news stories associated with floods and high-flows in Wyoming and Montana.
Study Links Major Floods in North America and Europe to Multi-Decade Ocean Patterns
The number of major floods in natural rivers across Europe and North America has not increased overall during the past 80 years, a recent study has concluded. Instead researchers found that the occurrence of major flooding in North America and Europe often varies with North Atlantic Ocean temperature patterns.