Upper Mississippi River System Flow Frequency Study Update

ST. PAUL DISTRICT - ROCK ISLAND DISTRICT - ST. LOUIS DISTRICT

The current flood flow frequency study for the Upper Mississippi River and Illinois River, completed in 2004, was based on data up to 1998. Since then, numerous major floods, including the historic flood of 2019, have occurred. Many communities between Dubuque, Iowa, and St. Louis, Missouri, have experienced top 10 flood crests in the past 20 years, with the Illinois River seeing similar unprecedented flooding.

To address these changes, this effort aims to update the flood flow frequency profiles for the following river segments:

  • Upper Mississippi River: From Birds Point (Mile 0.0) to Anoka, MN (Mile 864.8)
  • Illinois River: From Grafton (Mile 0.0) to Dresden Island Lock and Dam (Mile 271.5)

The study will utilize input data gathered during the previous flow frequency effort, augmented with new observed data from present, to create at least 25 years of new hydrologic data.

The U.S. Army Corps of Engineers regularly engages with watershed stakeholders who have expressed interest in better understanding how recent floods are affecting previously calculated frequencies. They have requested that this data to inform water resource decisions. Updating the study on the Upper Mississippi and Illinois rivers will have immediate benefits, ensuring that water resource decisions are made using current and accurate data, and providing significant value to the nation.

Status 

The project was partially funded in fiscal years 2021-2023 for development of a detailed scope of work, inventorying existing data and performing Part I of an Engineering Change Bulletin 2018-14 Climate Change Assessment. With funding received in fiscal year 2024, the project team will complete formulation of a Hydrologic Engineering Management Plan, consult with internal and external experts regarding the HEMP, and initiate development of a hydraulic routing model. 

If additional funding is provided, major tasks in this effort include: 

  • Development of a homogenous unregulated and regulated daily flow time series. 
  • Perform Part II of the Climate Change Assessment
  • Annual peak mainstream flow frequency analysis
  • Development of hydraulic profiles
  • Finalize report and study products

2004 Flow Frequency Study Final Report

Upper Mississippi River System Flow Frequency Study Final Report
Collapse All Expand All
Expand List item 5310Collapse List item 5310  Main Report
Expand List item 5721Collapse List item 5721  App. A - HEC Reports
Expand List item 5722Collapse List item 5722  App. B - St. Paul District Hydrology and Hydraulics
Expand List item 5723Collapse List item 5723  App. C - Rock Island District Hydrology and Hydraulics
Expand List item 5724Collapse List item 5724  App. D - St. Louis District Hydrology and Hydraulics
Expand List item 5725Collapse List item 5725  App. E - Kansas City District Hydrology and Hydraulics
Expand List item 9250Collapse List item 9250  App. F - Omaha District Hydrology and Hydraulics
Expand List item 9251Collapse List item 9251  App. G - HEC/IWR Sensitivity Studies
Expand List item 9258Collapse List item 9258  App. H - Public Involvement
Expand List item 9262Collapse List item 9262  App. I - Report 2, Uncertainty of Flood Frequency Estimates