The Wisconsin Department of Natural Resources and a group of environmental organizations announced a settlement agreement Monday that would require stricter environmental impact assessments of future data center developments and initiate a statewide review of how data centers use the state’s resources. 

In June, the Sierra Club and Midwest Environmental Advocates sued the DNR in Ozaukee County court, arguing that the agency approved the permits for Vantage’s massive data center currently under construction in Port Washington without conducting a proper environmental impact statement. 

“AI data centers are massive, thirsty, energy hogs and have popped up all over Wisconsin,” Elizabeth Ward, director of the Wisconsin chapter of the Sierra Club, said in a statement. “They could completely change our landscape and use unprecedented amounts of water and energy. Wisconsinites and our regulators need to understand the impacts and opportunities to reduce harm before allowing data centers to move forward. Wisconsinites deserve an informed, transparent process for decisions that could shape their communities and environment for decades.

A report this summer by the state Public Service Commission found that the Port Washington data center and data centers being built by Microsoft in Mount Pleasant and Meta in Beaver Dam are set to be responsible for a 40% increase in statewide energy demand over the next six years. 

As part of the settlement agreement in the lawsuit, the DNR will conduct full environmental impact statements of individual data center proposals moving forward and complete a statewide strategic analysis of how data centers consume resources. 

State law and the DNR’s administrative rules allow the agency to conduct such an analysis when conflicts arise over resource demands for a  “complicated or complex issue; an issue that is new to the state; an issue or policy that will likely lead to future department actions that will require an environmental impact statement; issues for which there is a high potential for legislation or new department policy and the planning and development of controversial resource-oriented projects.”

“What started as a lawsuit over the environmental review of one data center has become an opportunity to address the data center issue on a much bigger scale,” MEA attorney Michael Greif said. “Looking at these impacts holistically is important because the impacts of data centers are statewide. State regulators will now have to examine the cumulative impacts of data center development across Wisconsin.”

Wisconsin will become one of a few states assessing the statewide impacts of data centers on their resources. In July, New York Gov. Kathy Hochul signed an executive order that initiated a similar analysis and last December, the Maryland Legislature enacted a law that requires a number of state agencies to study “the likely environmental, energy, and economic impacts of data center development.”

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The U.S. Environmental Protection Agency is proposing to shift authority to regulate coal ash landfills in Wisconsin from the federal government to state environmental regulators.

The Wisconsin Department of Natural Resources sought approval in February of its program to oversee disposal of coal combustion residuals, or coal ash, from the state’s electric utilities. Wisconsin has six coal ash landfills that are owned by Dairyland Power Cooperative, Alliant Energy, Wisconsin Public Service and We Energies.

Coal ash is what’s left behind from burning coal at power plants to produce electricity. Metals or pollutants within that waste, including arsenic, lead and mercury, can contaminate groundwater without proper storage.

Anne Vogel, EPA’s regional administrator for its Chicago-based office, said the agency wants to eliminate duplicate regulation.

“It’s really about having to go to two different regulators and eliminating that barrier makes things more efficient, more cost effective for the management of these landfills in a protective way,” Vogel told WPR.

The state’s regulations must be at least as stringent as federal requirements, but they could be even more protective.

Wisconsin moved to streamline regulations under an update to rules for coal ash landfills in 2022, said Kate Strom Hiorns, director of DNR’s Waste Materials Management Program. Those changes incorporated 2015 regulations imposed by the Obama administration that addressed landfill design, groundwater monitoring and closure requirements.

“By submitting this and getting this program approval, it’s that recognition that our regulations are as protective as the federal regulations, and that the sites that are being regulated can be regulated for the most part solely under state regulators and inspections,” Strom Hiorns said.

Wisconsin utilities support a shift to one set of regulations for their coal ash landfills.

“Utilities in Wisconsin have been regulated by the state for many years; transferring this particular permitting authority from the federal to state government is a positive step for Wisconsin,” said Dairyland spokesperson Katie Thomson.

However, Cheryl Nenn with the environmental group Milwaukee Riverkeeper said she’s in favor of dual regulation.

“Given the changes in politics at the state level and the federal level, there’s some benefit to having that dual oversight,” Nenn said, highlighting the state’s adoption of federal regulations.

The Obama and Biden administrations strengthened coal ash regulations, including a 2024 rule that required oversight of inactive landfills. Under the Trump administration, the EPA has proposed rolling back and revising those requirements.

“They’d essentially remove or exempt a lot of these coal ash dump sites from regulation entirely, even though many of them are already showing evidence of groundwater contamination,” Nenn said.

Nenn said there has been groundwater contamination at the closed, unlined Cedar Sauk Ash Landfill in Ozaukee County that received coal ash from We Energies’ Port Washington power plant from 1969 to 1977.

The DNR has ordered the utility to address contamination and conduct sampling for boron and sulfate, which found levels of boron exceeded groundwater standards. We Energies has said the utility has seen “declining trends” for both in monitoring wells, and sampling indicates no effects to nearby private wells. 

Strom Hiorns said the state requires utilities to conduct groundwater sampling and has long monitored groundwater at closed coal ash landfills, which wouldn’t change under the federal proposal.

She said other landfills owned by We Energies and Alliant Energy have also exceeded preventive action limits or enforcement standards for groundwater. Those detections are tied to older parts of those sites or naturally occurring substances, such as boron or molybdenum.

Brendan Conway, a spokesperson for WPS and We Energies, said their landfills are actively monitored for groundwater impacts and managed in line with state and federal requirements. An Alliant spokesperson said it’s committed to full compliance.

Under the EPA’s proposal, Wisconsin would assume authority only for coal ash landfills. The EPA would continue to oversee coal ash ponds. The EPA is currently accepting public comments on its proposal to shift regulation to Wisconsin’s program. A virtual public hearing will be held Nov. 9.

This story was originally published by WPR.

EPA proposes shifting oversight of coal ash landfills in Wisconsin to state regulators is a post from Wisconsin Watch, a non-profit investigative news site covering Wisconsin since 2009. Please consider making a contribution to support our journalism.

The Wisconsin Department of Natural Resources issued a notice of violation to the Enbridge Energy Company for incidents in Iron and Ashland counties, where the company is working on a controversial reroute of its Line 5 oil and gas pipeline. 

The notice includes violations of permit conditions of the reroute construction project, and violations of state environmental laws for the unpermitted construction of a bypass around the Saxon Line 5 spill site. It covers laws involving state water quality, wetlands, navigable waterways, air quality, storm water and endangered resources protection.

The violations are alleged to have occurred from March 30 through Sept. 21 of this year. In August, a section of the pipeline leaked natural gas liquid near the town of Saxon, with drone video of the leak showing plumes of smokey vapor pouring out of an area where trucks and equipment were parked. Enbridge said that the leak occurred when an unoccupied truck rolled over an open excavation site near a valve project. Environmental groups fear that the leak could have been the largest of its kind in Wisconsin history.

 

 

The violation notice sets an enforcement conference, which is a standard step where the DNR and Enbridge will discuss the alleged violations. After the conference, the DNR can take further enforcement action such as issuing citations, referring the case to the Wisconsin Department of Justice for prosecution to seek forfeitures, or other court-related actions. 

A DNR press release notes that the notice of violation is separate from Enbridge’s responsibility under the spills law to respond to hazardous substances which may have been released during the August leak.

“These allegations are numerous and serious,” said Clean Wisconsin Attorney Evan Feinauer in a statement. “The DNR must now use the full force of its enforcement authority to hold Enbridge accountable and secure relief that addresses the significant harm to our environment Enbridge has caused.”

This article was updated with comment from Clean Wisconsin.

Following President Donald Trump’s executive order earlier this month to remove the gray wolf from the federal endangered species list, Wisconsin’s gubernatorial election will determine the direction of future management of the wolf population in the state. 

There are currently about 4,000 wolves across Michigan, Minnesota and Wisconsin, with the Wisconsin Department of Natural Resources estimating the state population number at about 1,162 wolves. The return of the wolf to the state is seen as a conservation success story after the animal’s extirpation in the 1950s. 

Trump attempted to delist the wolf during his first term in 2020, but a federal judge reversed that decision two years later. During the two years in which the wolf was delisted, Wisconsin held a controversial hunt of the animal in 2021 in which hunters surpassed the DNR’s quota in less than three days. A state law enacted in 2012 requires that Wisconsin hold a wolf hunt whenever the animal is not on the endangered species list. 

The question of Wisconsin’s wolf policy is one of the most heated in the state’s conservation politics. Farmers and residents in the northern part of the state, where most of the wolf population lives, are often more wary of living near the predator. But conservationists and the state’s Native American tribes have sought to protect the wolf as an important part of the ecosystem. 

During his time in Congress and the state Legislature, Republican candidate Tom Tiffany has regularly been a vocal advocate for hunting wolves. 

“His big priority is wolves. He wants to hunt wolves. I’m not kidding. He’s talked to me about it many times on the House floor,” Michigan Democratic Rep. Haley Stevens said on CNN last month. 

As a state legislator, Tiffany was a co-sponsor of a bill to mandate a wolf hunt and the first piece of legislation he ever introduced in Congress was a bill that would have removed the wolf from the endangered species list across the Midwest. 

After Trump’s executive order, Tiffany said in a statement that wolves are interacting too often with farmers and families in Wisconsin so they must be hunted. 

“Farmers are dealing with livestock depredations, families are losing pets, and wolves are showing up closer to homes,” Tiffany said. “Wisconsin has successfully managed wildlife for generations. It is time to get out-of-state judges and bureaucrats out of the way and let Wisconsin responsibly manage its wolf population.”

So far this year, Wisconsin has had 63 confirmed wolf depredations of livestock, pets and hunting dogs, according to DNR data. 

Tiffany’s campaign did not respond to a request for comment. 

Democratic candidate David Crowley, the Milwaukee County executive and a former Milwaukee-area state representative, has never represented a part of the state with a wolf population. After Trump’s delisting order, he told Wisconsin Public Radio he supports “commonsense efforts” to return management of the animal to the state. 

“While other parts of the country have different wolf populations and management needs, we need our agriculture, tribal, scientific, and impacted communities to come together to create a solution that works for Wisconsin,” Crowley said. “It’s time to follow the science and give impacted communities a seat at the table as we work together to be responsible stewards of Wisconsin’s gray wolf population.”

The decision over delisting will be made by the White House, U.S. Fish and Wildlife Service and the federal court system. Whoever Wisconsin’s next governor is will influence the state’s wolf policy through his power to sign legislation and appoint people to lead the Department of Natural Resources and sit on the Natural Resources Board. 

In 2023, the DNR and Natural Resources Board approved the first update to Wisconsin’s wolf management plan since the animal returned in the 1990s. Under the previous plan, the state set a “population goal” at 350 wolves, which at the time was seen as an aspirational aim as the state worked to reestablish the population. 

In the decades since that initial plan, the population far surpassed the goal. Anti-wolf advocates began to see that number as their preferred ceiling on the state’s wolf population. Under the current plan, the DNR decided not to set a specific numerical population goal but instead divided the state into zones in which policymakers will assess the biological, social and cultural factors to determine if the local population should be decreased, maintained or allowed to grow. 

The state uses a similar method for managing a number of other animals in the state, including bears. 

Republicans and their allies among hunting and farming organizations have vehemently objected to the method, repeatedly introducing legislation that would reinstitute the 350 wolf population goal. 

“Our policy says that our members would like to see a return to the population goal of 350, and we believe that even under the science the DNR has shown, that that’s a sustainable number,” Tyler Wenzlaff, director of national affairs for the Wisconsin Farm Bureau, told the Wisconsin Examiner. “We in no shape or form are advocating for their removal from the Wisconsin landscape. We know that they’re an integral part of the biological makeup of Wisconsin’s habitat, but we’d like to see some kind of return to a management where they’re controlled a little bit better.”

Wenzlaff said he’d like to see a “gradual decline” of the wolf population toward that number, particularly if Tiffany is the governor and Republicans maintain control of the Legislature. 

If Crowley wins and Democrats win majorities in the Legislature, Wenzlaff said the Farm Bureau would work to lobby environmental policymakers on the idea that the wolf has hit its biological and social carrying capacity in the state. 

“A wolf population beyond 1,200 to 1,300 is probably not socially acceptable either. And I think if you talk to the DNR, the current number has kind of hovered around this for a couple years now, so they believe that we’re at the biological carrying capacity,” he said. “And I think that anything more than that, you’ll start to see people start to lose that support for wolves once you start seeing animals being taken away, taken off their porch, or you start to see them out in the field when your son or daughter is waiting for the bus in the morning, it starts to get a little bit more real for people. And I think the expansion of the wolf habitat in the last wolf management plan will start to bring that home a little bit as the number increases.”

At a news conference earlier this month, Crowley said that while he believes the state can properly manage a wolf hunt with input from every side of the debate, Tiffany would go much further. 

“I do believe that we want to make sure that people can enjoy gaming and different types of recreational outdoor activities here in the state of Wisconsin,” Crowley said. “But I do believe you still need guardrails and making sure that people will be able to hunt wolves the way that they need to, but also making sure that we’re protecting this particular species as much as possible as well. And so, I do think that Congressman Tom Tiffany is going much further than I would like to go when it comes down to wolf delisting.”

Melissa Smith, executive director of the pro-wolf Great Lakes Wildlife Alliance, said in a statement that she would have preferred that Crowley take a strong stance against the delisting. Still, his position is  preferable to the lengths to which Tiffany would go. 

“Tom Tiffany has made stripping wolves of federal protection the centerpiece of his time in Congress, possibly being one of the most anti-wolf legislators in office right now,” Smith said. “While Wisconsin families are worried about the skyrocketing cost of living, he’s spent his energy on an issue that touches a few dozen of the state’s 58,000 farms. We expect these attacks on wolves to only intensify if given the power of the governorship.”

“David Crowley has also said he supports state management,” she added, “but he’s committed to following the science, and talked about bringing tribes, scientists and affected communities to the table and we’ll hold him to that. It’s clear Wisconsinites value wolves and what they bring to our state, and we look forward to working with the next governor to make sure that’s reflected in how they’re managed.”

The Line 5 oil and natural gas pipeline across northern Wisconsin went back online Monday, three weeks after a broken valve caused 1.3 million gallons of natural gas liquids to spill into the nearby Iron County town of Saxon, the pipeline’s operator Enbridge said in a news release. 

The spill occurred Aug. 25 when a truck rolled forward and broke the valve as crews worked on the controversial reroute of Line 5’s path across the state from Canada. Enbridge immediately began working to bypass the broken valve and get the pipeline back up and running despite warnings from the state Department of Natural Resources that it was doing that construction without the proper permitting. 

The DNR issued a notice of noncompliance to Enbridge last week ordering it to halt its work. Despite that warning, Enbridge completed the work and said in its news release that “work continues at the site focused on safe access, environmental testing and remediation.” The company said it has worked closely with federal and local agencies to protect health and safety and that “we continue to work” with the DNR on the “relevant permitting and separately on environmental conditions at the incident site.” 

“Ongoing environmental monitoring at the site continues,” Enbridge stated. “Wildlife has not been impacted. Testing of surface water and from a nearby residential well continues to show no impacts. Water monitoring wells continue to show no contamination. Soil and water monitoring are in place, as are plans to test, remove and properly dispose of the soil in the trench.”

Since the spill, the company has argued it needs to get the pipeline back up and running as soon as possible because the fossil fuels it transports are too important. 

“Line 5 is critical infrastructure, securely supplying 10 refineries and propane production facilities that deliver energy to millions of people in the Midwest and Great Lakes regions,” the company news release states. 

Meanwhile, environmental activists, members of the Bad River Band of Lake Superior Chippewa and elected officials have continued to argue that the spill is confirmation that the pipeline has always been a risk to Wisconsin’s environment and should be permanently shut down.

The Wisconsin Department of Natural Resources has told the oil and gas company Enbridge to halt construction on the Line 5 pipeline across northern Wisconsin after a massive spill of natural gas liquids in Iron County late last month. 

The spill, which occurred near the town of Saxon and at 1.3 million gallons of natural gas liquids was the largest in the company’s history, was caused when an unoccupied truck rolled over a valve while crews were doing construction work. The company is in the process of rerouting Line 5 off the Bad River tribe’s reservation — a controversial project which has triggered numerous challenges to the DNR and federal permits. 

Since the spill, environmental activists, tribal members, candidates for office and elected officials in both Wisconsin and Michigan have renewed their calls for the pipeline to be shut down. 

After the spill, Enbridge began working to bypass the damaged valve so the pipeline could again be used to transport Canadian oil and gas. On Wednesday, the DNR issued a notice of noncompliance to the company, noting that Enbridge was constructing the bypass without the proper permits from the DNR. 

In the notice, and in an accompanying letter from DNR Secretary Karen Hyun, the agency said that it had told the company on three separate occasions it could not conduct the bypass work without approval from the state, and possibly from both the county and federal governments. 

The notice states that the bypass construction involves matting placed in nearby wetlands and close to Spoon Creek, which is considered a navigable waterway regulated by state law. 

In her letter, Hyun said she was “deeply concerned and incredibly frustrated” by Enbridge’s actions, especially the potentially harmful effects caused by the “significant discharge” of pollutants known as volatile organic compounds — which can be harmful to people’s health and the local environment. 

“Enbridge has continued to add to the growing list of environmental concerns and violations, demonstrating disregard for the environment, human health, and the statutory authority of the department,” she wrote. “Regarding the Line 5 reroute construction, Enbridge has caused additional discharges to the environment since my earlier letter, which have caused continued frustration and profound unease for the department and the people of Wisconsin. Additionally, at the location of the Line 5 Natural Gas Liquids (NGL) spill on August 25, Enbridge has made the decision to start unpermitted construction of a bypass, despite the extensive efforts of the DNR to educate Enbridge on the necessary permits and approvals for this bypass construction and a commitment to review submitted materials in a timely matter. Based on this pattern of noncompliance demonstrated by Enbridge, my concern over the environmental impacts of Enbridge’s activities over the past weeks has only heightened.”

In a statement, Enbridge spokesperson Juli Kellner said the company is working “around the clock” to clean up the spill site and return the pipeline to service. 

“Enbridge continues working towards both priorities related to the third-party line strike near Saxon, Wis. — the safe control and remediation of the incident site and completing a temporary bypass to allow the pipeline to return to service, which will help resolve energy supply disruptions,” she said. “Around the clock work on both priorities is being done in parallel. Line 5 is critical infrastructure delivering energy to millions of people in the Midwest and Great Lakes regions. We continue to work with the Wisconsin DNR on relevant permitting and separately on environmental conditions at the incident site.”

Rob Lee, an attorney for Midwest Environmental Advocates who has worked on the challenges to Enbridge’s Line 5 permits, said that the company doesn’t get to decide that restoring the pipeline is more important than following state law. 

“Enbridge knew it needed authorization before it started this work. The DNR told the company that repeatedly. Enbridge went ahead anyway. That shows extraordinary disregard for Wisconsin’s environmental laws and for the state agency charged with enforcing them,” Lee said. ““Enbridge cannot simply decide that getting Line 5 back in service is more important than following Wisconsin law. They’ve been out there moving earth, crossing waterways and disturbing wetlands without permits. They need to stop treating environmental requirements as obstacles to work around and start following the law. If they don’t, DNR should revoke the permits for the reroute.”

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Most of the 29 people killed in ATV/UTV crashes so far this year had never completed an off-highway vehicle safety course, according to the latest data from the Wisconsin Department of Natural Resources.

And DNR officials say that 15 of those who died were over the age of 60 — meaning they were among those who are not required to take safety courses under state law.

DNR data shows most of the people killed in off-highway vehicle incidents were not wearing seat belts or helmets, and frequently alcohol was a factor in the crashes. Those are all aspects the state’s safety courses try to explain to riders.

Jacob Holsclaw, the DNR’s off-highway vehicle administrator, said that’s a notable trend and one the state is starting to look at.

“Many of the crashes could be prevented simply by adopting a safety code of conduct,” Holsclaw said. The DNR offers tips and class information on its ATV/UTV page. 

The DNR recommends all operators to take a safety class, no matter their age.

The data for 2026 shows most people killed in ATV/UTV incidents were born before Jan. 1, 1988.

“What we’re seeing is a majority of the folks involved in these fatal or serious injury crashes were born before that date,” Holsclaw said. “So the class would have been optional.”

Under the law, riders over 38 are not required to take courses.

Only five people killed in OHV incidents were younger than 38, according to state data.

Three UTV/ATV operators were confirmed by state officials to be safety-certified at the time of the crash, according to DNR’s data for 2026. 

There are still five cases with unclear safety certification, but the DNR said their status is pending at this time.

Randy Harden, the president of the Wisconsin ATV/UTV Association, said his group has been working with the DNR to improve safety in the state’s riding population.

He says it’s often difficult to get older Wisconsinites to take protective gear seriously.

“That’s our challenge,” he said. “How do we keep communicating effectively to get the message over?”

Only three women died in UTV/ATV incidents this year. Two were over 65; the youngest was 40. All three women died on public roadways in Wisconsin.

Most of the fatalities were men, with a total of 25. The oldest was 83. One child died at 10 years old. 

And while 29 deaths this year were directly tied to crashes that happened this year, DNR officials said an additional OHV-connected fatality occured when a person died this year from injuries in a crash that occurred years ago, Holsclaw said. The medical examiner listed that death as a result of an ATV crash.

The top three kinds of fatal crashes were: rollovers, with 15 crashes; motor vehicle collisions with six; and people being ejected from the vehicle in four crashes, according to DNR data.

Harden says many riders mislead themselves into thinking they’re safe enough to ride in a machine without a helmet.

In reality, Harden says the vehicle doesn’t have air bags and riders have a real risk of being thrown out of the vehicle in a crash. 

“Even if you have your seat belt on, then your noggin is taking a beating in that roll cage,” he said. 

It’s not clear how many fatalities reflected in 2026 crash report data had alcohol in their system — but Holsclaw said it’s common in many OHV crashes.

As of Aug. 14, the DNR webpage for crash reports shows, out of 29 fatalities, 21 incidents where the BAC level is listed as “Pending.”

“It can take months for us to get alcohol or drug results back, and so that’s why we leave those open until we get that confirmation,” he said. 

But, Holsclaw said in a typical year, the department finds alcohol is a factor in between 40% and 50% of fatal crashes.

“That’s a pretty big percentage,” he said.

Five fatal crashes were confirmed to have involved alcohol, according to the DNR data. 

For comparison, Minnesota’s Department of Natural Resources says that state has had only seven fatal crashes so far this year. In 2025, MDNR recorded 22.

This story was originally published by WPR.

More than half of people killed this year in Wisconsin off-road vehicle crashes were over 60 is a post from Wisconsin Watch, a non-profit investigative news site covering Wisconsin since 2009. Please consider making a contribution to support our journalism.

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Wildfires in northern Minnesota and Canada have caused some of the worst air quality on record for Wisconsin. The entire state remains under an Air Quality Advisory for fine particulate matter from wildfire smoke until noon on Friday, according to the Wisconsin Department of Natural Resources. 

As of 2 p.m. Thursday, most of the state’s air quality was in the “very unhealthy” or “hazardous” Air Quality category. That means that everyone, not just sensitive groups, should avoid outdoor activities, the DNR said.

In areas near Superior, the Air Quality Index rose above 800, while parts of eastern Wisconsin including Milwaukee and Kenosha measured above 650. National Weather Service meteorologist Benjamin Sheppard told Wisconsin Watch these levels are some of the worst on record. 

“What we’ve heard from some of our partners is that the Air Quality Index values that we’re seeing are definitely either never before seen or up there,” Sheppard said. “I’ve been working here for three years, and I’ve seen nothing anywhere near that high.” 

Index values in Wisconsin have exceeded the records set by wildfires in June 2023, DNR spokesperson Craig Czarnecki said in an email, noting that the figures “will still need to be quality assured.” At that time, levels peaked at 273, which means concentrations in Superior and the Milwaukee area have more than doubled. 

The U.S. Centers for Disease Control and Prevention recommends setting up a portable air cleaner or filter in a room that can be closed off from outside air and setting your air conditioner  to recirculate mode if possible or close the outdoor intake damper. 

Fine particulate matter, also known as PM2.5, is a main pollutant released from wildfire smoke that can enter the bloodstream. Dr. Joan Schiller, a member of Healthy Climate Wisconsin and retired medical oncologist, told WPR this can exacerbate lung conditions.

“I don’t think people realize how far away you can be from the fire itself and still have health problems,” Schiller said. “These health problems typically manifest themselves as respiratory problems, such as exacerbation of COPD or asthma or emphysema.” 

How can I check the air quality in my area?

The Environmental Protection Agency monitors the air around the country and compiles an air quality index, or AQI.

Here’s what to know about the index and how to keep tabs on your area, especially in U.S. regions dealing with smoke from Canadian wildfires.

What does the air quality index measure? 

The index rates how clean or polluted the air is each day. The EPA uses this measure to keep tabs on five kinds of air pollutants. The main concern from the wildfire smoke is fine particle pollution. These particles are tiny enough to get deep into the lungs. They can cause short-term problems like coughing and itchy eyes and, in the long run, can affect the lungs and heart.

What do the numbers and colors mean? 

The index categories typically only run from zero to 500 – although levels have reached well above 500 in multiple parts of the state. The higher the number, the worse the air quality. That range is broken down into six color-coded categories. Green or yellow — in the zero to 100 range — the air is pretty clear. Once it gets up to orange, the air quality could be a concern for sensitive groups like children, older adults or those with health conditions.

In the red and purple zones, the air quality is considered unhealthy for everyone.

And if the index gets to maroon — at 301 or above — pollution levels are hazardous.

At these high levels, take precautions to avoid breathing in the dangerous air. That can mean reducing your outdoor activities, running air purifiers inside and wearing a well-fitting mask like an N95 when you’re outside.

What’s the air quality right now? 

Check AirNow.gov, which updates every hour. The site shows a real-time map of the air quality across the country and also includes a forecast for the day ahead. The map pulls in measurements from a network of air monitoring stations across the country. States and cities may also offer more local guidance.

How long will smoke last in Wisconsin? 

According to Sheppard and the National Weather Service (NWS), a southerly wind on Friday means smoke is anticipated to retreat from west to east  – likely bringing an end to the advisory for much of the state. 

“With those southwest winds, the air is going to get kind of clearer and healthier in a southwest to northeast manner,” Sheppard said. “Areas further north and east in Wisconsin are going to be most likely to hang on to that smoke.” 

Areas along Lake Superior may also need to have the advisory extended, NWS said. But Sheppard said winds could bring back a second wave of smoke to the rest of the state as soon as Saturday. 

“The weather models tentatively are telling us that the second batch of smoke could be as strong, or perhaps even worse,” he said. 

The Associated Press contributed reporting, as did Hongyu Liu of Wisconsin Watch.

Wildfire smoke brings hazardous air quality in Wisconsin. Here’s how to stay safe is a post from Wisconsin Watch, a non-profit investigative news site covering Wisconsin since 2009. Please consider making a contribution to support our journalism.