Setting Backburn and Setting Off Sprinkler Systems Saving Mariposa Grove
Yosemite National Park – Fire News – July 12, 2022 – The Washburn Fire was reported on July 7th, near the Washburn Trail in the Mariposa Grove area of
Yosemite National Park. Dry conditions and hotter weather patterns helped this fire spread quickly closing access the Yosemite’s West entrance and endangering many of Yosemite’s Iconic symbols near the Mariposa Grove. As the fire expanded to over 3200 acres over the weekend specific attention was give to saving the Mariposa Grove region, home to some of the largest most iconic trees left on earth.
While structure wrap is not currently being used on the giant sequoias, firefighters are proactively protecting the Mariposa Grove through the use of a ground-based sprinkler system. This increases the humidity in the area around the trees and combined with the removal of ground fuels, the ground fire risk is greatly reduced. Yosemite’s fire management program has for many years utilized a wide variety of methods to reduce the fuels and minimize the risk of fire to the over 500 mature giant sequoias as well as the entire National Park.
Terrain and Fuels: The fire is burning in difficult terrain which presents accessibility issues for firefighters. Heavy fuel loading from a period of high tree mortality has resulted in a large number of standing dead and fallen trees which create hazardous conditions for firefighters. The current fire location does not provide a large number of natural barriers which are often used to slow or stop the spread of a fire. Consequently, a great deal of hand and dozer line is being constructed.
Aircraft Incident: On Saturday, July 9th a tree branch was sent into the air from the powerful updraft produced by the fire. As it dropped back to earth, it narrowly missed two firefighting aircraft. Fortunately, there were no injuries and no damage. We are all grateful for the hard work and risks taken by everyone involved with the firefighting effort.
Evacuations & Closures: Wawona, Wawona Road (Hwy 41) south of Yosemite West, and the Mariposa Grove are closed until further notice. All other areas of Yosemite National Park are open. Use El Portal Rd (Hwy 140) or Big Oak Flat Rd. (Hwy 120 East) or Tioga Rd (Hwy 120 West) to enter Yosemite. EXPECT SMOKEY CONDITIONS WITHIN THE PARK.
The Rest of the Park Remains Open: Reservations required; visit www.recreation.gov. We appreciate the patience of the public as visitors experience longer waits at the other entrances while the south entrance remains closed.
Located in the southern portion of Yosemite, the Mariposa Grove of Giant Sequoias is the largest sequoia grove in Yosemite and is home to over 500 mature giant sequoias. The national park idea is rooted in the Mariposa Grove. In 1864 President Lincoln signed legislation protecting the Mariposa Grove and Yosemite Valley for “public use, resort, and recreation.”  For the first time in our nation’s history, the federal government set aside scenic natural areas to be protected for the benefit of future generations. Later added to Yosemite National Park in 1906, the Mariposa Grove is a popular destination within the park. For more information, please visit the Yosemite National Park’s Mariposa Grove WebpageÂ
Outlook
| Planned Actions | Continue direct handline construction where possible and prepare for indirect line when needed. Utilize offensive firing operations along primary control lines when appropriate. Defend Wawona Point and the Community of Wawona. Protect Miraposa Grove. Establish contingency lines through Long Valley to Star Mine |
| Projected Incident Activity | 12 hours: The continued warm and dry conditions produced active-to-very during the day that will extended into the night due to poor relative humidity. Significant activity was observed on the northwest and northeast corners of the fire south of the S. Fork. Merced River. Light winds are allowing sustained backing on slopes, flanking, and torching with spotting. Downslope and down drainage wind flow will provide smoke in the valleys especially during the night.24 hours: Warming and drying will continue to provide active fire behavior throughout the period, with the burn period extending into the night time hours due to low relative humidity. Light winds will provide sustained backing on slopes with flanking, torching and spotting. Continued fire spread may be expected on the east side of the fire in the South Fork Merced River drainage.48 hours: Warm and dry conditions combined with poor-fair night time relative humidity will produce conditions for active to very active fire behavior on uncontained portions of the fire perimeter. Expect sustained backing, active flanking, more frequent torching with spotting, and short headfire runs likely.72 hours: Increased warming and drying that will maintain active to very active fire behavior potential. Likely increase in fire behavior to include group torching, short torching/crown runs on wind aligned slopes, and spotting to .5 miles Anticipated after 72 hours:Peak warming and drying period late in the week will provide active to very active fire behavior on uncontained portions of the fire. |
Video and image credit to the National Parks Service. All videos and images property of the NPS.
