Passing the test: June flood showed successes of mitigation and work left to do

When the rain started falling in late June, it was falling on ground already saturated by all the rain that had come before. What came next was the largest flood event since 2004, which inundated Austin and the surrounding areas.

It was also the first major test for mitigation efforts that the city and county agencies put into place in the years following 2004, and reflected mostly wins but also those areas that required more work.

“I think they worked very well,” said Austin City Engineer Steven Lang. “It’s always hard to gauge what it would have been like had it not been for the improvements that had been made.”

By the time the rains dwindled on Saturday, June 23, the National Weather Service had recorded through its observer network that Austin had received 6.5 inches of rain.

However, reports also showed just how localized the systems were, with some areas surrounding Austin receiving eight inches of rain along with a smattering of reports hitting close to 10 inches.

By the time it was all said and done, the Cedar River in Austin crested at 20.6 feet, four feet below 2004’s record of 25 feet.

Other measurements taken in and around Austin on Turtle Creek and Dobbins Creek also pushed record marks.

Flood waters ultimately infringed on several areas in Austin, including the area of Oakland Avenue East and Fourth Street where the Hardy Geranium and Stuttgart Tan & Travel were impacted along with Triple J. Auto Sales.

Also because of the heavy and rapidly-falling rains, there were reports of water in basements. As water rose, areas like Lafayette Park and the Wildwood Park area were under water and in the county, rising water threatened LeRoy made some roads impassable for a time.

However, the impact overall seemed to be greatly reduced compared to 2004.

“There would have been many more impacts,” Lang said. “(Mitigation) made a difference, a positive difference.”

Following 2004, the city began pushing forward with efforts to control large flood events in the future. One of the largest included the purchase of over 200 homes in Austin in the floodplain.

Places like downtown Austin and the Wildwood Park area all saw extensive changes over the years. Running parallel were berm projects built alongside areas where flooding was more prone to happen including the extreme north end of Main Street in the area of Barley’s Restaurant and Kuehn Motor Sales.

Further south on Main Street near Mill Pond, the road was raised two feet putting the lowest point at the height of the 2004 flood. Flood walls were built into that project to help stem and control any flooding.

Along Turtle Creek, berms were also erected to further protect homes.

Flood pumps were also installed, which help move water during major events.

However, mitigation work outside of Austin was just as important. Over the years, the Mower Soil and Water Conservation District has established an extensive network of projects north of Austin including berms and water retention ponds through partnerships with landowners.

“Everything, all the projects, worked exactly how we anticipated,” said Cody Fox, district manager. “There was nothing out of the ordinary.”

Drone photo shows the amount of water held by retention pond in Mower County during this last flood event. Photo courtesy of the Mower Soil and Water Conservation District

Aerial shots taken by SWCD staff showed just how much volume the ponds were able to hold, including one pond that held 140 acre feet of water, which Fox had compared to 140 football fields with a foot of water on them.

Even at the height of the rainfall, Fox said he was confident that the retention ponds would do what they were built for.

“Unless something weird comes up, I don’t worry about them,” Fox said. “They are built to withstand a 100-year event or more.”

Like Fox, Lang felt good about the preparedness of Austin while not getting too overconfident.

Just days ahead of the weekend, the city also had some heads-up of what could happen when a heavy rainfall pushed the Cedar River up to eight feet.

“It forced us to start thinking about things,” Lang said. “It was helpful to have those events five days prior. It put us in a good position when the rain event came Friday night.”

While both Lang and Fox were pleased that mitigation projects worked, both also admitted there is still work to be done and more places examine. Despite mitigation efforts, many in Austin still wound up with water in the basements despite inflow and infiltration efforts which the city started in 2018 that required homeowners to stop pumping water directly into the sanitary sewer system (inflow) as well as shoring up old pipes with cracks and holes that were leaking water into the system (infiltration).

When that effort wraps up this year, Lang said the city will start working with the firm WHKS to examine possible solutions to try and stem those issues in the future.

Other issues include a ditch that runs behind Ellis Middle School and along Sixth Avenue SE that became inundated following the heaviest of rains. Lang said the city has $100,000 in Capital Improvement Plan money set aside in 2025 to study that area with $1.5 million in the 2026 budget to implement work that comes out of the study.

They will also be evaluating how the wastewater treatment plant is able to handle all the water flowing in from major rain events.

During this event, the plant had to discharge water into the Cedar River to avoid further back-ups, something Lang said they don’t like to do, but he added that the water drained into the river is heavily deluded with clear water that comes into the plant.

On a normal day, around four million gallons of water a day flows through the plant. During this event, 20 million gallons flowed. Of that 16 million gallons was clean water and four million was wastewater.

The Minnesota Pollution Control Agency was alerted to the need for such steps to avoid further, more serious back-ups.

On June 23, a late afternoon rain storm highlighted another area for the city to evaluate. Prior to that, with the Cedar River and Mill Pond rising, Lang said they had to close gates and check valves to make sure water from the river didn’t affect property on the other side of the berm network.

When those afternoon rains fell, delivering a couple inches of rain in just about 45 minutes, it caused Main Street to be quickly covered over. The situation developed so quickly that a vehicle became stuck in the rising waters.

“It just wasn’t able to keep up with that,” Lang said of the pumps. “We’re going to be evaluating that. What were the pumps sized for and is there anything better we can do?”

Meanwhile, Fox said that in the county there are more plans to hopefully add more retention ponds to further stem any flows that come into Austin.

“It further exemplifies the fact that we’re not done yet,” he said. “We’re actually talking to several landowners. We’re not building any projects this year, but we’re hoping for next year.”

The work on developing these projects can span several months or more, but Fox said that he hopes that the success of current retention ponds can show landowners that these efforts work and are worth putting on their property.

“One of the things is just making sure the projects work and are maintained and do what they are supposed to,” Fox said. “I think it’s going to help us moving forward.”

“Now we know what the water needs to do,” Fox added. “We’ve had another rain event. The hope is, down the road at some point in the future when we have an event like this, that hopefully we have more projects in place.”

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