June 12 (UPI) -- For the first time in more than a century, Colorado's San Juan National Forest will close Tuesday due to a nearby wildfire that's grown to more than 22,000 acres.
The closure order marks the forest's first closure in its 113-year history.
Forest service officials said access to the public and most administrative staffers would be closed off -- including the use of forest campgrounds, day use areas, roads and trails.
Officials said the Colorado 416 wildfire, which started around June 1, has grown to 22,131 acres and is advancing at a rate of 1 mph. The fire has grown about 5,000 acres since Sunday. It is just 15 percent contained.
More than 900 firefighters are working to suppress the blaze. More than 2,200 homes have been evacuated.
Forest supervisor Kara Chadwick said the decision to shut down the park was a difficult one, but noted conditions at the park have continued to worsen.
"The indices our fire team uses to predict fire danger are at historic levels well before we can expect any significant moisture from the seasonal monsoons," San Juan fire official Richard Bustamante said.
"Under current conditions, one abandoned campfire or spark could cause a catastrophic wildfire, and we are not willing to take that chance."
Forest spokeswoman Cam Hooley said a chance of thunderstorms and showers from Thursday through Sunday won't bring enough moisture to reopen the forest.
"The weather at the end of this week is probably not anything big enough to make much of a difference," Hooley said. "It will all be based on the weather; my best guess is whenever the monsoon moisture arrives, we'll be able to get out of the closure."