A city committee is looking for flood data in the Ebner Coulee area of La Crosse’s South Side as it works to get property owners out of the floodplain.
The city’s Floodplain Advisory Committee authorized assistant city engineer Bernie Lenz to mail out a survey next week to the owners of 500 parcels of land in the 1.13 square miles in the Ebner Coulee floodway, asking property owners and residents to contribute any information they can on the July 2017 flood.
The goal of the survey is to provide information to the Wisconsin Department of Natural Resources as experts determine whether homes in the area should be required to purchase flood insurance, said Brad Woznak, a consultant with Short Elliott Hendrickson who was hired by the city to study the floodway mapping and modeling.
Previous modeling puts residents in the floodplain. The city contends there are flaws with that analysis.
“Based on the results, roughly 88 homes should have been inundated because of that event,” Woznak said. “Since it sounds like there’s very little damage or flooding reported as that, the modeling appears to overpredict the runoff coming out of the coulee.”
The storm was the most intense in the past 20 years, Woznak said, dropping roughly 6.3 inches of rain in 11 hours.
“That’s great to have an event that recent and that intense to base our stuff off of,” Woznak said.
SEH has been working to create a more accurate model to determine which properties fall in the 100-year flood plan, using methodology developed by the U.S. Geologic Survey. However, as the city prepares to make its case and ask the DNR to sign off on a Letter of Map Revision, it wants as much information as possible.
“We’ve got a fair amount of data now, but anything we can get from the citizens is definitely going to help,” Lenz said.
In particular, Woznak wants to see any high water mark data or photos people may have, which will better allow SEH’s model to match what actually happens.
“The risks shown on the map should reflect that of the real world,” Woznak said.
The city urged people to fill out the survey even if they had no flooding whatsoever.
“Even if there was nothing, that can also be an important piece of data,” Woznak said.
The city also will accept flood data for any other major rain event in the city.
“Any available data can never hurt,” Woznak said.
Neighborhood associations in the area have also volunteered to help get the word out.
“Any and all methods of obtaining info would be good,” Woznak said.
After the survey goes out, people will have a couple weeks to fill it out and return it to the city.
Woznak expects the process of getting the South Side properties out of the floodplain to take up to two years, assuming the DNR agrees with the Letter of Map Revision.
“I’m hopeful,” said committee chair and council member Andrea Richmond. “If there’s a way we can get a lot of homes in that area out of the floodplain, it’s a big cost savings for people.”
Unfortunately, there’s no way for a similar methodology to help those in the floodplain on La Crosse’s North Side, said Lenz.
“I’m hopeful. If there’s a way we can get a lot of homes in that area out of the floodplain, it’s a big cost savings for people.” Andrea Richmond, committee chair and council member