Flooding and High-Flow Conditions in Wyoming and Montana Active
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.
Below are data or web applications associated with floods and high-flows in Wyoming and Montana.
Below are publications associated with floods and high-flows in Wyoming and Montana.
Montana StreamStats
Water-surface profile and flood boundaries for the computed 100-year flood, lower Salt River, Lincoln County, Wyoming
Summary of floods in the United States, January 1992 through September 1993
Methods for estimating magnitude and frequency of floods in the southwestern United States
Summary of floods in the United States during 1990 and 1991
Nationwide summary of US Geological Survey regional regression equations for estimating magnitude and frequency of floods for ungaged sites, 1993
Methods for estimating magnitude and frequency of floods in the southwestern United States
Flood boundaries and water-surface profiles for the computed 50-, 100-, and 500-year floods, Childs Draw and tributary near Cheyenne, Wyoming, August 1991
National water summary 1988–89 — Hydrologic events and floods and droughts
Use of paleoflood investigations to improve flood-frequency analyses of plains streams in Wyoming
Flood boundaries and water-surface profile for the computed 100-year flood, Swift Creek at Afton, Wyoming, 1986
Summary of floods and droughts in the United States
Streamflows in Wyoming
Below are data or web applications associated with floods and high-flows in Wyoming and Montana.
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.
- Overview
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 - Science
Below are other science projects associated with floods and high-flows in Wyoming and Montana.
- Data
Below are data or web applications associated with floods and high-flows in Wyoming and Montana.
- Publications
Below are publications associated with floods and high-flows in Wyoming and Montana.
Montana StreamStats
About this volumeMontana StreamStats is a Web-based geographic information system (http://water.usgs.gov/osw/streamstats/) application that provides users with access to basin and streamflow characteristics for gaged and ungaged streams in Montana. Montana StreamStats was developed by the U.S. Geological Survey (USGS) in cooperation with the Montana Departments of Transportation, Environmental QuaFilter Total Items: 50Water-surface profile and flood boundaries for the computed 100-year flood, lower Salt River, Lincoln County, Wyoming
The water-surface profile and flood boundaries for the computed 100-year flood were determined for a part of the lower Salt River in Lincoln County, Wyoming. Channel cross-section data were provided by Lincoln County. Cross-section data for bridges and other structures were collected and compiled by the U.S. Geological Survey. Roughness coefficients ranged from 0.034 to 0.100. The 100-year flood wAuthorsKirk A. Miller, John P. MasonSummary of floods in the United States, January 1992 through September 1993
This volume contains a summary of the flooding in the upper Mississippi River Basin during the spring and summer of 1993 and 36 articles describing severe, widespread, or unusual flooding in the United States from January 1, 1992, to the end of the 1993 water year, September 30, 1993. Each flood is described to an extent commensurate with its significance and the availability of data on the hydrolAuthorsDonald V. ArvinMethods for estimating magnitude and frequency of floods in the southwestern United States
Methods were developed for estimating magnitude and frequency of floods at gaged and ungaged sites in the Southwestern United States. Estimating equations for ungaged sites were developed by transferring information from gaged to ungaged sites using multiple regression and a hybrid method developed during this study. The methods and analysis are described, and information from more than 1,300 gageAuthorsBlakemore E. Thomas, H. W. Hjalmarson, Scott D. WaltemeyerSummary of floods in the United States during 1990 and 1991
This volume contains 50 articles describing severe, widespread, or unusual flooding in 28 of the 50 States during 1990 and 1991. Each flood is described to an extent commensurate with its significance and the availability of data on the hydrology and the damages. Each article includes one or more maps showing the general area of flooding. Most articles include tables of data that allow comparisonAuthorsPaul Robert Jordan, L. J. CombsNationwide summary of US Geological Survey regional regression equations for estimating magnitude and frequency of floods for ungaged sites, 1993
For many years, the U.S. Geological Survey (USGS) has been involved in the development of regional regression equations for estimating flood magnitude and frequency at ungaged sites. These regression equations are used to transfer flood characteristics from gaged to ungaged sites through the use of watershed and climatic characteristics as explanatory or predictor variables. Generally these equatiAuthorsM.E. Jennings, W.O. Thomas, H. C. RiggsMethods for estimating magnitude and frequency of floods in the southwestern United States
Methods have been developed for estimating magni- tude and frequency of floods at gaged and ungaged sites on streams in the southwestern United States. Estimating equations for ungaged sites that apply to small drainage basins were developed by transferring information from ungaged sites using techniques such as multiple regression and a hybrid method developed during this study. Drainage area, mAuthorsB. E. Thomas, H. W. Hjalmarson, S. D. WaltemeyerFlood boundaries and water-surface profiles for the computed 50-, 100-, and 500-year floods, Childs Draw and tributary near Cheyenne, Wyoming, August 1991
No abstract available.AuthorsGeorge F. RitzNational water summary 1988–89 — Hydrologic events and floods and droughts
National Water Summary 1988-89 - Hydrologic Events and Floods and Droughts documents the occurrence in the United States, Puerto Rico, and the U.S. Virgin Islands of two types of extreme hydrologic events floods and droughts on the basis of analysis of stream-discharge data. This report details, for the first time, the areal extent of the most notable floods and droughts in each State, portrays thByWater Resources Mission Area, Pennsylvania Water Science Center, Oklahoma-Texas Water Science Center, Kansas Water Science Center, Utah Water Science Center, Dakota Water Science Center, Central Midwest Water Science Center, Upper Midwest Environmental Sciences Center, Upper Midwest Water Science CenterUse of paleoflood investigations to improve flood-frequency analyses of plains streams in Wyoming
No abstract available.AuthorsM. E. CooleyFlood boundaries and water-surface profile for the computed 100-year flood, Swift Creek at Afton, Wyoming, 1986
Flood flows on Swift Creek near Afton, Wyoming, were analyzed. Peak discharge with an average recurrence interval of 100 years was computed and used to determine the flood boundaries and water surface profile in the study reach. The study was done in cooperation with Lincoln County and the Town of Afton to determine the extent of flooding in the Town of Afton from a 100-year flood on Swift Creek.AuthorsJames G. Rankl, Joe C. WallaceSummary of floods and droughts in the United States
This paper describes a current national analysis of streamflow data being conducted by the U.S. Geological Survey to identify and map, in a consistent State-by-State format, the frequency and areal distribution of major floods and droughts in the United States. The work is being performed as the latest in a series of National Water Summaries published as Geological Survey Water-Supply Papers. TheAuthorsMarshall E. Jennings, Richard W. PaulsonStreamflows in Wyoming
A description of the occurrence and availability of surface waters in Wyoming is presented along with explanations of both streamflow-data collection and methods for estimating streamflow characteristics at gaged and ungaged sites. Mountain ranges separate the major drainage basins and have a significant effect on the quantity of precipitation and the volume of runoff that occurs in Wyoming. PerenAuthorsH. W. Lowham - Web Tools
Below are data or web applications associated with floods and high-flows in Wyoming and Montana.
- News
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.