Until the permanent Flood Management System is built, the City of Cedar Rapids uses several tools to reduce the risk of flood damage.
Officially, the flood stage in Cedar Rapids begins with a 12-foot river level. This flood stage occurs almost annually during the spring thaw. In the past, the City has successful protected up to the 20-foot river level because we have experienced this level many times.
With new temporary flood barriers (see details below), the City can protect up to a 24-foot river level in most areas along the Cedar River. However, a flood level greater than 24-feet will cause widespread flooding because of the flat topography of Cedar Rapids.
The flood stage is measured locally by four U.S. Geological Survey (USGS) river gauges installed in the Cedar River in Waterloo, Vinton, Palo and Cedar Rapids. These four gauges improve flood forecasting accuracy and reliability.
To view current river levels, go to the National Weather Service Advance Hydrologic Prediction Service Web site.
If a major flood occurs, the existing floodwalls and levees along the Cedar River are supplemented with sand- and water-filled temporary flood barriers. These temporary barriers can add up to four feet of additional protection, which means we can raise the level of flood protection to a 24-foot level in most areas along the Cedar River.
The temporary flood barriers will reduce the risk of flood damage, but will not prevent all flood damage. In the event of a major flood, the City will call for neighborhood evacuations before installing temporary barriers.
City crews and contractors can install nearly three miles of temporary flood barriers in four main locations: Time Check Neighborhood area, east and west sides of downtown and Czech Village area.
5-in-1 Dam Operations
The City of Cedar Rapids has set operational procedures approved by the Iowa Department of Natural Resources for the operations of the 5-in-1 dam during high water events.
The dam has both underwater gates and slide gates that operate to let more water pass through the dam. The underwater gates raise and lower automatically throughout the year to maintain a consistent pool of water above the dam to support river recreation. When the water starts to rise these underwater gates lower automatically as a first response.
The slide gates on either side of the underwater gates can only be raised after the water below the dam has reached a depth of 10 feet. Raising the slide gates before this threshold could jeopardize the structural integrity of the bridge. Additional slide gates are opened as the water continues to rise. When water below the dam reaches a depth of 12 to 12.5 feet, all slide gates are opened and the underwater gates remain fully lowered until the water starts to recede.
Additional Flood Preparedness Measures
In addition to the new temporary flood barriers mentioned above, the City has purchased additional water pumps, an additional sandbag making machine and storm pipe plugs and valves to reduce sewer backflows. The City now has 46 water pumps, seven "duckbill" valves and dozens of plugs on hand, in additional to maintaining a stock pile of filled sandbags year round.