Mullen Fire has grown 10,000 acres in 24 hours, 'very close' to Rob Roy Reservoir - Casper, WY Oil City News
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Mullen Fire has grown 10,000 acres in 24 hours, ‘very close’ to Rob Roy Reservoir

Sunday morning, 9/20 in Medicine Bow-Routt National Forest, the Mullen fire having grown to more than 13,000 acres (Medicine Bow-Routt National Forest, Twitter)

UPDATE: This article now includes the latest map of the fire perimeter released by the US Forest Service at noon Sunday, 9/20/2020. It also updates evacuation notices given at 2:00 pm.

CASPER, Wyo — Aerial assessments Sunday morning, September 20, estimate the Mullen Fire burning in the Medicine Bow-Routt National Forest has grown to 13,835 acres. That’s 10,000 more than estimates 24 hours earlier.

“It appears the fire has not yet reached Rob Roy Reservoir, but is very close,” the US Forest Service said in an Inciweb update around 11:00 a.m. Sunday. The reservoir is a source of Cheyenne’s municipal water supply.

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“We do not know the impact of the Mullen Fire at this time, but the location suggests there may be some adverse effects to the City of Cheyenne’s water collection system and water quality,’ said Clint Bassett, Water Treatment Manager, in a release from the city’s utilities board.

Air resources are continuing to drop retardant in the Rambler subdivision area, which includes homes and cabins and is adjacent to the Rob Roy Reservoir, according to the Sunday morning update.

High winds, dry conditions, abundant fuels have contributed to the Mullen Fire burning largely unchecked up drainages in the forest since it was first reported mid-day Thursday.

Mullen Fire perimeter at noon Sunday, 9/20/2020 (US Forest Service)

Fuels include live and dead lodgepole pine, with abundant deadfall due to beetle-kill and wind events. There are very few natural fuel breaks in the forest of lodgepole pine. The fire grew mostly to the north, northeast, and south on Saturday the update said, and some rain showers did occur Saturday night.

The National Weather Service (NWS) in Cheyenne forecasts that that west winds in the area Sunday are expected to be between 15 and 20 mph, with higher gusts. Aerial resources were forced to abandon their efforts Saturday night due to high and shifting winds from a passing cold front and an abundance of thick smoke. NWS says showers and thunderstorms could reach the area on Tuesday.

The Keystone area south of the Rob Roy Reservoir was ordered evacuated at 2:00 pm. Pre-evacuation notices were given for Centennial Valley, including:

  • Centennial
  • Albany
  • Northwest to the Snowy Range along Highway 130
  • private land along Fox Creek Road,
  • all areas west of Highway 11 in the valley.

“Please be prepared to leave immediately if an evacuation order is called for,” the agency said.

The US Forest Service expanded it’s closure of the area Saturday night up across the Snowy range, north to the Highway 130 corridor, and south to the Platte River Wilderness, which includes:

  •  Six Mile Gap Campground 
  •  Pelton Creek Campground.
  • The Douglas Creek Trail
  • Douglas Creek Trail
  • Pelton Creek Trailhead
  • Pike Pole Trailhead
  • Platte River Trail
  • Routt Access Trailhead
  • Six Mile Trailhead
Medicine Bow Forest closure update Sept 19, 2020 (US Forest Service.)