Electricity provider Great River Energy is already operating at "medium threat response level," and could kick into a higher gear and sequester its most critical workers if the spread of COVID-19 gets worse.

Such scenarios are playing out across the U.S. electric utility sector, one of society's bedrock industries. Certain utility workers, those in control rooms or out on power lines, can't work from home.

Maple Grove-based Great River and other Minnesota electricity providers are trying to keep distance between those workers like many other businesses. But unlike others, they have plans to essentially shelter and feed workers on site if the need arises.

Sequestration "seems like a logical step when it gets bad enough," said Mike McFarland, Great River's director of enterprise risk management and the company's crisis commander for the COVID-19 outbreak.

Xcel Energy, Minnesota's largest electric utility, and Minnesota Power also have employee-sequestration plans. Such plans are common in the industry, and utilities in some parts of the country have implemented them, according to the Edison Electric Institute, an industry trade group.

"There are a few examples of companies moving to sequestration already, and there are more in the process," said Scott Aaronson, the electric institute's vice president for security and preparedness.

The threat to utilities is employee contagion, that COVID-19 "will cause a reduction in workforce," Aaronson said.

Major electric utilities have plans for all sorts of disasters, including pandemics. Great River, Xcel and Minnesota Power have all activated theirs.

Great River, a wholesale cooperative that ultimately supplies power to nearly 700,000 customers, put together its pandemic plan after the H1N1 influenza outbreak of 2009.

Since then, there have been tweaks as information was gleaned from other epidemics. On Feb. 28, Great River activated the plan at its lowest level, ratcheting it up to medium on March 12, McFarland said.

Great River told employees who can work from home to do so. But at electricity providers, control centers must be staffed while line workers, outage fixers and other physical plant employees also must be on site.

For instance, Great River's control room at its largest electricity plant, Coal Creek in Underwood, N.D., has five employees per shift. Its main system control center in the Twin Cities requires three workers.

At the current threat level, those control rooms are washed down and sanitized after each shift, McFarland said. Employees take measures not to come in contact with each other at shift changes, using separate room entrances and exits in some cases.

At Coal Creek, which employs around 260, about one-third of the plant's workers must be on site to keep the giant coal-fired power plant operating.

Great River would contemplate sequestering employees if the company moves to "high threat response level," McFarland said.

Under its sequestration plan, workers could spend two-week stints in the workplace. "It's not like you are stuck there until it is over," McFarland said.

Nuclear-power generators require the most workers, and Xcel's plants in Monticello and near Red Wing respectively employ 600 and 800 people. "Our current number of operations and maintenance employees at [the nuclear] plants is not that different from pre-COVID-19 levels," Xcel said in a statement.

Power plants are considered critical infrastructure by the federal government. "Most plant employees are deemed essential," too, said Xcel, which has 1.3 million Minnesota electricity customers.

"In the event we need these employees to work extra shifts, we are creating sleeping areas so they can rest," the company said. "If circumstances change, we are prepared to sequester our critical employees in plants, control rooms and control centers to protect them from the spreading illness."

Duluth-based Minnesota Power, with about 145,000 customers in northeastern and central Minnesota, also said it is prepared for sequestration if need be.

"Our plans include preparation for this type of event should it become necessary, and the signposts would include major absences like the 50-60% range, which we have not experienced to date," the company said in a statement.

Mike Hughlett • 612-673-4613