Infrastructure designed with climate change in mind survives flood - Duluth News Tribune

Culverts designed with climate change in mind survive flood - Duluth News Tribune | News, weather, and sports from Duluth, Minnesota

Infrastructure designed with climate change in mind survives flood

Dozens of culverts and roads washed out during June 18's storms, but a culvert replacement project in Lake County built to aid brook trout and withstand 100-year-rain events held firm.

FINLAND, Minn. — It wasn’t all that uncommon for Hockamin Creek to overwhelm the Heffelfinger Road crossing, damaging the road and cutting off residents who live down the road.

The two culverts under the gravel road in Crystal Bay Township, a 200-square-mile township of 600 people just west of Finland, were undersized and perched above or near the waterline. Erosion issues surrounded the culverts.

The culverts also prevented brook trout from passing through the creek, a tributary to the Baptism River, which travels through Tettegouche State Park before emptying into Lake Superior.

So state and local officials designed a replacement culvert that considered both brook trout habitat and 100-year-rain fall events. Completed in fall 2022, the culvert is more of a bridge than a traditional culvert — it has an open bottom and a wide span.

And it’s working.

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As heavy rain on June 18 washed out dozens of Northland roads and culverts, the Finland area saw some of the heaviest rain totals of between 5 and 6 inches of rain within 24 hours.

Even so, the new culvert “performed wonderfully,” said Tara Solem, district manager of the Lake County Soil and Water Conservation District.

“I’m really impressed at how well they work,” said Douglas “Pudge” Perfetto, Crystal Bay’s road supervisor. “It saved us a lot of misery.”

With climate change already increasing precipitation and extreme rain events in the region and climate models showing a wetter future, conservation experts said building infrastructure with climate extremes in mind will help protect people, property and natural resources.

The Heffelfinger Road culvert is one of 17 such projects near Finland designed to help improve brook trout habits as the region and its streams warm, a response to a study of climate models that found the fish’s habitat could decrease by 34% along the southern half of the North Shore by 2060, according to Dean Paron, stream habitat supervisor at the Minnesota Department of Natural Resources.

The efforts appear to be working.

“We're seeing fish migrating great distances to reach cold water,” Paron said.

Holding up in a flood is a bonus.

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“By designing for fish passage and designing for changing hydrology for fish passage, the side benefit, or the co-benefit, is you have stable infrastructure,” Paron said.

Looking forward, not backward

Infrastructure has largely been constructed to withstand scenarios based on historical precipitation data instead of future climate projections, leaving stormwater systems more vulnerable to the expected increase in rainfall and extreme events due to climate change.

But Suzi Clark, a climate adaptation and resilience extension educator at the University of Minnesota’s Climate Adaptation Partnership, said that’s starting to change.

Over the past 5-10 years, more projects are considering climate projections, Clark said.

“I hope that people will look to the future, not the past,” she said. “We have a long list of examples where people use historic climate data to plan things like buildings and stormwater infrastructure, and oftentimes that’s just the industry standard, and I understand that. But in order for us to be resilient to the increasingly intense events in the future, we need to look forward with our planning and not back.”

While many infrastructure projects have relied on historical rain data, older projects didn’t consider anything.

Luke Heikkila, Aurora’s city administrator, said that’s especially true for the city's 100-year-old or older stormwater systems. Things like impervious surfaces and stormwater retention ponds, which are standard when considering developments today, weren’t considered back then.

“Whenever it rains, you’ve got all this old infrastructure that’s not designed to handle what today’s rains are, and some of them weren’t even designed to handle any rain,” he said.

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But the four-square-mile Iron Range city of just under 1,700 people is looking to change that by first modeling current stormwater, and then constructing new and fortifying existing infrastructure.

The cost of climate change

Updating infrastructure is not cheap, but climate investments now could prevent more costly damage from climate-change-fueled events later.

Kate Knuth, the MPCA's climate director, pointed to an estimate by the United Nations Panel on Climate Change that found every dollar invested in climate-resilient infrastructure could save six dollars.

Knuth said that even now insurance fees and public budgets are rising as climate change fuels more extreme weather.

“We do expect, by putting investments in and considering the impacts of climate change and helping communities prepare, that it will help reduce costs. … It is traumatic for individuals and families and communities to deal with major flooding, and it’s also expensive for individuals, families, communities and government,” she said.

Still, the upfront costs can be a deterrent, especially for small communities.

However, state and federal grants aim to lessen the burden.

The source of Aurora’s grant came from a $100 million pot of money approved by the Minnesota Legislature last year. The MPCA is awarding grants first for planning and then for the construction of climate-resilient projects.

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Heikkila said he wants to fix things the right way — not with a patchwork of changes throughout town — and the model could be continually updated to reflect any developments in town and the latest climate projections.

“By using that model, it makes us do the right project instead of the wrong project so you’re not doing something twice where, ‘Hey, we put this culvert in, and five years later it gets washed out again. Well, dang. We should have put in a bigger size,’ ” he said. “So you’re putting in the correct materials right away.”

Back in Crystal Bay Township, the replacement of the culvert and another down the road was originally estimated at $400,000, but final costs tripled to $1.2 million due to a number of factors, such as a cement shortage due to the war in Ukraine and the flooding in May 2022.

The project would have been cost-prohibitive for the township, but funding through the U.S. Fish and Wildlife Service’s National Fish Passage Program, Clean Water Land and Legacy Amendment and contributions from several conservation organizations have made it possible.

But with warming and more extreme future weather events, Solem, of the Lake County SWCD, said building with climate resiliency needs to be front of mind.

“It impacts all of us in many different ways,” Solem said. “Everything from the natural resources we value to just being able to move about our daily lives and not have infrastructure damage stranding people and making things more difficult and costly. Climate resiliency is just the way we need to plan and think on a daily basis with our projects.”

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