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Forecasts, reality and teacups

It remains impossible to accurately predict where and when flooding will occur because it is not possible to accurately forecast the weather more than a few days ahead. The amount of rain and variations in temperature over just a few days, for example, can strongly influence the timing and extent of runoff.  A combination of weather conditions, including heavy snow and unexpected warm rain, contributed to the historic floods of 1964 and 1996.


The Corps uses both short-term (10-day) and long-term (3-month) runoff forecasts to help determine the amount of space needed in its flood storage reservoirs to reduce flood risks. Year-round, the Corps uses the short-term forecast, produced by the National Weather Service Northwest River Forecast Center, to make the timeliest decisions possible.


The National Weather Service Northwest River Forecast Center is responsible for issuing official flood warnings and forecasts. The public is encouraged to visit their website for information about rising river levels. The Corps uses information on this site to help estimate river flows. Check out: http://www.nwrfc.noaa.gov/.

Contact information

Phone: 503-808-4510

Email Public Affairs about
Water management

Reservoir teacups

Visit river basin “teacup” diagrams for real-time reservoir levels. Each project’s smaller “teacup” includes observed inflow, precipitation levels and its specific rule curve. The diagrams also show releases from dams for the past seven and 30 days.


Lower Columbia River Basin 

Rogue River Basin  

Willamette River Basin

Simulations set the stage

SimRes is a simulation tool that considers these factors that the Corps’ reservoir regulators must consider in real life:

  • Flood risk management
  • Fish and wildlife enhancement
  • Irrigation
  • Municipal and industrial water supply
  • Water quality
  • Hydropower generation
  • Navigation
  • Recreation

The Corps’ simulations also incorporate random weather patterns so reservoir regulators can adapt to the changing conditions, such as heavy rain or drought.

Give it a try

The simulation is easy to use with a java-enabled browser. To operate the simulation, adjust the gate that controls the flow of water through the dam. Use the up and down arrows on the simulation’s control panel to increase or decrease the flow of water through the dam. As the gates open hydropower generation increases and the power meter registers this increase. Keep in mind that certain changes in water releases result in a poor and even deadly environment for fish. The height of the water also affects river navigation and boating.

To run the simulation, click here: http://www.nwd-wc.usace.army.mil/nwp/simres/. You can also download a zip file of the java applet for offline use.