Water levels at the Coralville Reservoir are expected to crest just under the spillway next week, and a little more rain could become a huge problem. The Army Corps of Engineers at the Coralville Dam controls how much water flows out of the reservoir. Operations Manager Dee Goldman says they look at a variety of factors in determining how much water to release.
“Local communities downstream and what their levels are and what they can withstand. We want to get rid of the water just as quick as we can, but we want to do it in a safe manner,” Goldman says. If they out too much water, there are floods downstream — and if they let out too little — the reservoir fills up and the water can go over the 712-foot spillway, and they lose control of the water flow.
That’s what happened in 2008 when there was massive flooding. “We would be discharging our maximum outflow of 20,000 CFS, plus whatever was going over the spillway. It’ s a tremendous amount of water,” according to Goldman. Goldman says if anything, water levels have become more volatile and harder to predict in recent years as the watershed has changed.
“What used to be all forested is a lot of cropland, more development, all of that means that that water that would normally soak into the ground is now getting run off, which means our lake comes up a lot quicker and lot faster,” Goldman says.
The Corps doesn’t expect water to breach the 712-foot capacity next week, but they say they’re keeping an eye on rainfall. The University of Iowa has been putting flood protection measures in place as a precaution.
Governor Terry Branstad added eight more counties to the disaster proclamation list as part of the recent storms and flooding. The latest counties to join the list are: Benton, Grundy, Johnson, Louisa, Lyon, Mitchell, Poweshiek and Wapello.
The Governor’s proclamation allows state resources to be utilized to respond to and recover from the effects of these storms, including for removal of debris and wreckage on publicly or privately owned land that may threaten public health and safety. The proclamation of disaster emergency also activates the Iowa Individual Assistance Program for Grundy, Johnson, Mitchell, Poweshiek and Wapello.
The program provides grants up to $5,000 for households with incomes up to 200 percent of the federal poverty level. Contact the Iowa Department of Human Services for more information. The governor issued a disaster proclamation earlier for 13 counties: Buena Vista, Butler, Cherokee, Floyd, Ida, Iowa, Jasper, Mahaska, Marshall, Plymouth, Sioux, Tama and Wright.