US coal plants slashed their mercury pollution. North Dakota accounts for a big share of what remains
North Dakota ranks second only to Texas in mercury emissions from EPA-regulated power sector sources. Driven by the low-grade coal found in North Dakota, several of the state's power plants rank among the heaviest mercury-polluting coal facilities in the country.
BISMARCK — Over the last decade, power plants across the country have slashed the amount of mercury they release into the atmosphere. But of the electricity sector’s remaining mercury emissions, North Dakota’s fleet of coal-fired power plants contributes a disproportionate share.
Coal-burning facilities in North Dakota have cut their mercury emissions from more than 2,300 pounds in 2010 to 847 pounds in 2020, according to data supplied by the state Department of Environmental Quality. That mirrors a national trend, as some coal plants around the country have been replaced by natural gas and the rest have had to adapt to tighter environmental policies from the federal government.
While coal-fired power is no longer the country's largest source of mercury pollution , North Dakota plants dominate recent catalogs of the biggest mercury emitters in that sector. In 2020, North Dakota ranked second only to Texas in mercury emissions released by facilities regulated under the U.S. Environmental Protection Agency’s mercury and air toxics standards, according to agency data . And an analysis of the country's largest power producers, compiled last year by the consultancy Environmental Resources Management, showed that four of the country’s top six mercury-emitting coal plants were in North Dakota in 2019. Coal Creek Station, the largest coal-fired power plant in the state, ranked second.
Dave Glatt, director of the state Department of Environmental Quality, said all six coal-fired power plants in North Dakota are in compliance with the EPA’s current mercury standards, and noted that while those plants may have high mercury emissions compared to facilities in other parts of the country, they account for a small cut of national totals, which include sources beyond the power sector. He added that emissions from North Dakota facilities are relatively high compared to other states in large part due to the low-grade coal, called lignite, that fuels the state’s power plants. Lignite contains higher concentrations of mercury than coals mined in most other parts of the country, and, as a result, is subject to a less stringent EPA standard.
Pending rules at the EPA could require coal plants to cut their mercury output even beyond the major reductions of the last decade. Earlier this year the agency reaffirmed its authority to curb mercury emissions from power plants , reversing a Trump administration policy.
Glatt said all of North Dakota's power plants have continued to operate with their mercury controls even during the Trump administration rollback, and added that the state isn't seeing even minor environmental or health impacts at the current emissions levels.
Still, some environmental advocates argue that even today’s diminished mercury pollution is too much.
Elena Craft, a senior director of climate and health at the Environmental Defense Fund, said that while the power sector is moving in the right direction, there's still a long way to go. And there are plenty of examples of power plants operating within the limits of their permits whose emissions nonetheless drive harmful environmental and health consequences, she added.
"Ultimately, we want to get to a place where we have zero emissions, right?" said Craft, who is based in Texas. "At some point, I think on some of these facilities, getting to that point on a coal-fired power plant is much more difficult than getting to that point" for a different type of electricity generation.
The EPA estimates that facilities regulated under its mercury and air toxics rule, which applies to hundreds of power plants around the country , released 2.6 tons of mercury in 2020, down from 29 tons a decade earlier. Close to 15% of the 2020 total came from North Dakota.
Half-empty or half-full?
The coal plant smokestacks that tower over the North Dakota prairie are designed to release pollutants high into the atmosphere, diffusing them over an area that can span thousands of miles.
Volumes of mercury emissions are minuscule compared to other pollutants like carbon dioxide, but small amounts can go a long way. Once released, the element can migrate into bodies of water both locally and in far away countries, building up in an ecosystem's food chain upon entering animal systems. A neurotoxin, the element becomes a hazard to people mainly through fish consumption, and it can be especially harmful to the brain development of children.
John Pavlish, a senior vice president at Midwest Energy Emissions Corp. and former research adviser at the University of North Dakota’s Energy and Environmental Research Center, stressed the coal sector's drastic reductions in mercury pollution of the last decade. The costs of further cutting the pollutant from coal plants would far exceed the benefits, he said.
But if regulations do require plants to further cut their mercury emissions, North Dakota facilities likely have some room to improve, said Pavlish, whose job involves selling mercury controls to power plants. Unlike the lignite-burning plants of Texas, where mercury contents tend to be somewhat higher, the current regulatory standards are “not overly challenging for North Dakota plants,” he said, even if matching the low mercury levels of non-lignite plants would be “very difficult.”
The Environmental Defense Fund, which recently published findings that also showed several North Dakota coal plants to be among the heaviest mercury-emitting plants nationally in 2020 , has argued that a higher mercury standard for lignite plants is "something EPA should correct to protect the health of all Americans."
Though Coal Creek Station tallied the second largest coal plant mercury emissions in both the Environmental Resources Management and Environmental Defense Fund data, the 1,100 megawatt facility has seen its mercury pollution cut by more than 60% over the last 10 years, from a recent high of 900 pounds in 2013 to 340 pounds in 2020, according to DEQ data.
Jennifer Charles, an environmental services leader at Coal Creek, highlighted that sharp reduction in an interview with The Forum. Coal Creek uses a combination of a mercury control and a pre-combustion refining process to remove impurities from the coal. Charles said the plant's owner Great River Energy has been involved in research to reduce mercury emissions for more than 20 years, and said the plant remained in compliance with the EPA's Mercury and Air Toxics rule even during the Trump administration rollback.
“We take the environmental impacts of our operation very seriously, and we’re proud of what we have done to reduce those emissions and comply with those mercury limits,” she said.
Also in the top six mercury-emitting coal plants nationally in 2019, according to the Environmental Resources Management analysis, were North Dakota's Antelope Valley Station, Leland Olds Station and Milton Young Station. Those plants have each seen cuts to their mercury emissions of more than 60% since 2010, which DEQ Division of Air Quality Director Jim Semerad said are thanks to capture systems that trap the pollutant before its release from the smokestacks.
A spokesperson for Basin Electric, which operates Leland Olds and Antelope Valley, said in a statement that the two plants are in compliance with federal regulations and that the co-op has “a long-standing commitment to environmental compliance.” A spokesperson for Minnkota Power Cooperative, which operates Milton Young Station, similarly said the plant meets all regulatory standards and noted significant mercury emissions reductions over the last decade. “Technologies are continually explored to reduce overall emissions levels,” the co-op said.
Overall mercury emissions have declined in North Dakota through the decades as both power plants and smaller combustion sites have replaced coal with natural gas, Semerad said. Great River Energy retired its Stanton Station coal plant in 2017, and Montana Dakota Utilities' Heskett Station, in Mandan, is in the process of retiring its coal-burning units and ramping up natural gas generation.
Major reductions in power plant mercury pollution in recent years have put a new spotlight on the much smaller and harder to reach emissions that remain, Semerad said.
“You could argue that this glass is half empty (or) half full,” he said. On the one hand, mercury emissions from North Dakota coal plants have been slashed in the last decade; on the other hand, North Dakota’s mercury footprint looks pretty large compared to other states, he said.
Up-to-date research on the contents of mercury in North Dakota waters and its fish is thin, making it difficult to say with confidence how the neurotoxin’s presence in the state’s rivers, lakes and wetlands has changed as power sector mercury emissions have fallen off, said Peter Wax, an environmental scientist with the DEQ’s Division of Water Quality.
Wax said DEQ's readings of mercury in North Dakota fish are dated. The department posts recommended limits on how much fish from North Dakota waters people can eat before risking health consequences from the mercury, with the last such advisory published in 2003 and the most recent fish tissue samples taken in 2009. Wax said the 2003 fish consumption guidance is conservative, but added that the department is looking to update its measurements and guidance in the coming years.
Even so, the environmental scientist said part of the challenge is that current mercury levels are so low that they don't register in the DEQ's water readings. He added that the existing data suggests the neurotoxin has likely either held stable or declined in the years since more rigorous testing was done.
Still, “it’s not an easy emissions-to-fish story,” said Sarah Janssen, a geochemist with the U.S. Geological Survey’s Mercury Research Lab in Wisconsin.
Local sources like coal plants can contribute to a body of water's mercury contents, but so can far off sources in other countries. And Janssen, whose team has conducted past studies in North Dakota, said a long list of variables determines how mercury cycles through a given ecosystem, including the amount of organic matter present, fluctuations in water levels and the eating habits of fish and other wildlife.
Research in other parts of the country, including the Great Lakes Region of the Upper Midwest, does suggest that mercury levels in fish and wildlife have abated as local emissions have been curbed, Janssen said. But without more robust data, it’s hard to know whether North Dakota has seen a similar trend, she said.
Readers can reach Forum reporter Adam Willis, a Report for America corps member, at firstname.lastname@example.org.