Dave Couture filled his shovel full of 310-degree mixture of cold-mix blacktop and dumped it in a basketball-sized crater on East Fourth Street in Duluth.

The water and ice that once filled the pothole sizzled and turned to steam as Couture gently patted the blacktop down with the blade of his shovel. It's a process he and others in the city of Duluth's street maintenance department will repeat thousands of times this spring as potholes pop up throughout Duluth streets.

"Trying to flatten the road as best as we can," Couture said.

Couture, along with three fellow crew members, had already used about three and a half tons of blacktop, or one hopper's worth, by late morning Tuesday, but that was only enough to fill about a block's worth of potholes near the intersection with North 34th Avenue East, where some of the largest potholes sat unfilled. Members of the crew expected their workday would be spent filling potholes at just that intersection, using at least three hoppers worth of asphalt.

"Boy, that water keeps coming out of the banks, we got to keep fixing the holes," Couture said, gesturing toward the melting piles of snow lining the street. "Once it stops, then it's not quite so bad."

But until then, the department expects up to four crews working each day filling potholes.

This year's pothole season is particularly bad, said Geoff Vukelich, a lead worker for the department.

He blamed record snowfall, weeks spent below zero, a sudden warm-up and rain for the sudden popping up of potholes throughout Duluth.

"This year is bad," Vukelich said. "It is worse than most years ... if for no other reason than we were plowing snow for a month and a half straight and we never got to patching. The (potholes) that were open just got bigger, and ones that we could have maybe curbed a bit are now just as bad as the bigger ones."

Vukelich, who refers to the largest potholes as "bombs," said the city prioritizes fixing potholes on busy thoroughfares in the city over quiet residential streets and "bombs" that could damage a car rather than shallow holes in the asphalt.

But eventually, Vukelich said, crews will get to all of the potholes. The city has about 450 miles of roads to maintain after all.

"People want their stuff fixed and I get it, but we're just trying to trying to mitigate it the best we can," Vukelich said. "It's not perfect, and I don't claim it to be perfect at all, because we are a reactionary source at this point."

Vukelich estimates the department of 38 people will use 100 tons of blacktop each week just to fill potholes and could use a total of 500 to 600 tons to fix all of the wintertime potholes.

People can alert the city of potholes using its pothole hotline, which Vukelich said he closely monitors.

As for damage that cars could receive after hitting a pothole, the city might be able to cover that too - but it's not likely.

Duluth City Attorney Gunnar Johnson said that with the annual proliferation of potholes in the spring comes an annual increase in claims against the city for damage to vehicles.

Though many such claims are filed, he said payouts aren't typical.

"The city is not liable when they decide to use money to buy a police vehicle instead of filling a pothole," Johnson said. "For the most part, the city is not liable for damages if you hit a pothole driving down the street, and it breaks the strut on your car or pops your tire."

This "discretionary immunity" often means that while it is the city's responsibility to repair and maintain public roads, it may not be the city's responsibility to pay for damages those roads may cause. Occasionally, though, the city's insurance adjuster, or in some cases a judge, may agree with someone filing a claim. The city's self-insurance covers such payments.

"There is a process in which people can file a claim, and we don't dissuade people from doing that," Johnson said. "We try to treat people fairly - if someone is entitled to be paid on a claim, we do that. If we have a strong defense not to pay them on a claim, we don't."

Back at the intersection of Fourth Street and North 34th Avenue East, Vukelich and Couture both expect they'll be back refilling the same potholes next week.

"We live on the side of a hill that's a giant rock," Vukelich said. "You can have the best engineering in the world, the water goes downhill. There's nothing we can do about that."

News Tribune reporter Brooks Johnson contributed to this report.