A plague outbreak in prairie dog colonies has partially closed the popular Rocky Mountain Arsenal National Wildlife Refuge, frustrated Phish fans scrambling for Labor Day weekend camping spots and threatens Colorado’s endangered black-footed ferret population.

The plague scare prompted health officials to disallow overnight camping and restrict parking at Dick’s Sporting Goods Park in Commerce City, where Phish will play Aug. 30-Sept. 1. The venue is located adjacent to the refuge.

Plague has not been found in prairie dog colonies at Dick’s Sporting Goods Park, and the popular group will still hold its performances as scheduled.

The ferret population most threatened lies just outside Denver at the 15,000-acre refuge, which closed in July while staff applied insecticide to kill fleas before partially reopening several weeks later. The closed areas are clearly marked and will likely reopen in early September, according to a statement on the refuge’s website.

A refuge spokesperson said it is unknown if its ferret population has been impacted. He said the refuge will survey its ferret population in the next few days. He added the refuge's ferret population is on the opposite end of the refuge from where the infected prairie dog colony is located, which is next to Dick's Sporting Goods Park.

Aran Meyer, Fort Collins Natural Areas Department wildlife biologist, said the sylvatic plague virus is a “serious threat’’ to black-footed ferret populations.

“It’s double faceted for ferrets,’’ Meyer said. “Prairie dogs are susceptible, which means ferrets are susceptible because they live together, and the ferrets’ main prey base is prairie dogs.’’

Last week, Meyer led a nocturnal survey of the ferret population at the city’s Soapstone Prairie Natural Area and adjacent Meadow Springs Ranch 25 miles north of Fort Collins. He said plague was not detected in the population. Soapstone/Meadow Springs is one of two sites in Colorado to host sylvatic plague vaccine trials through Colorado Parks and Wildlife. Meyer said an insecticide is also used to keep plague from impacting the population at the sites.

Plague was last found on Soapstone in a remote section of the natural area in 2015.

“We are concerned about the threat of plague, but between the insecticide and vaccine, we are using the tools we have in the toolbox to prevent it,’’ Meyer said.

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In 2014, 42 ferrets were released on the nearly 19,000-acre Soapstone Prairie Natural Area and 26,600-acre Meadow Springs Ranch.

In 2015, 32 ferrets were released at the Rocky Mountain Arsenal National Wildlife Refuge. Another 22 were released in 2016. More than 300 ferrets have been released at six sites in Colorado since 2013 to bolster the wild population, which was thought to be extinct until ferrets were found near Meeteetse, Wyoming, in 1981. The original Colorado reintroduction site in the northwest part of the state died out due to plague.

The National Black-Footed Ferret Conservation Center in northern Larimer County is home to the nation’s captive breeding facility.

Plague remains one of the main threats to increasing wild ferret populations. Earlier this month, it was found in a prairie dog town on private property in Weld County, where it killed a large number of prairie dogs. However, the colony was not one of the ferret reintroduction sites.

Plague is common at some levels in prairie dog towns but doesn’t pose a significant risk until an outbreak occurs. Human cases of the disease are nearly all located in the western U.S., with the Four Corners area the nation's hot spot.

It is rare for humans to contract the various forms of plague — seven per year, according to the CDC — and few humans die of the disease in the U.S. However, in 2015, a 16-year-old Poudre High School student died of septicemic plague.

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Plague safety tips

Use insect repellent on skin and clothes.

Do not camp near rodent nests or burrows.

Hunters and trappers should wear gloves when handling dead animals.

Do not allow dogs and cats to roam free.

Use a flea and tick preventative on dogs and especially cats as recommended by your veterinarian.

Consult your physician if you become suddenly ill within seven days of visiting a plague-affected area.

Plague symptoms

Sudden onset of high fever, chills, headache, muscle aches and weakness

Tender and extremely swollen lymph nodes

Nausea, vomiting and diarrhea

Inform your health care provider about possible exposure. Plague is curable when diagnosed early but can be fatal unless treated promptly.

Miles Blumhardt looks for stories that impact your life — be it news, outdoors, sports, you name it he wants to report it. Have a story idea, send it his way. Email him at milesblumhardt@coloradoan.com or find him on Twitter at @MilesBlumhardt.