Due to recent precipitation in the area in the last several weeks, including the unsettled weather forecast for the next several days, fire managers will monitor the area and ignite the planned prescribed burn when prescription parameters are at optimum levels.
This year, March is the ideal timeframe for prescribed fire due to minimal snowpack and rain. Typically, fuels and vegetation would be too wet to burn this time of the year. However, the current drought makes this March an ideal burning season. Additionally, the burn area is surrounded by the Hetch Hetchy Road and previously burned areas that were affected by the Rim Fire.
The primary objective of the prescribed fire is to treat vegetation and fuels around the buildings and other infrastructure of the O’Shaughnessy Dam. The burn unit is located near the Hetch Hetchy Road and will protect infrastructure at Hetch Hetchy from potential wildfires. Additionally, this prescribed fire is designed to reduce surface and “ladder fuels” that allow ground fire to leap to the tree canopy and cause crown fires. Once treated and maintained, this unit will offer a “fuel break” for firefighters to safely protect structures at the O’Shaughnessy Dam.
Since 1930, multiple lightning ignitions have been suppressed in the area, indicating that wildfire does present risk to the developments at Hetch Hetchy. The area surrounding the unit previously burned with low to moderate intensity during the 2013 Rim Fire and multiple lightning fires have been managed nearby for resource objectives in recent years.
A smoke management plan has been submitted to the Tuolumne County Air Pollution Control District (APCD) and a burn permit will be issued. Only localized smoke impacts to the Hetch Hetchy Road and O’Shaughnessy are anticipated. The exact date of the burn will be determined in collaboration with the APCDs to find optimal weather to disperse smoke away from populated areas. At the discretion of the APCDs, smoke monitors may be deployed in smoke sensitive communities to monitor air quality. Mariposa and San Joaquin County APCDs have been notified of the burn as well.
The Hetch Hetchy Road will remain open during the burn; however traffic control will be necessary during roadside operations. Visitors to the area are urged to drive with caution as firefighters, fire equipment, smoke and debris may be present on the roadway. The Hetch Hetchy campground will close for one to two days during the operation. However, the Hodgdon Meadow Campground, which is on a first-come, first-served basis, will remain open during the burn.
Fire crews from Yosemite National Park, other national parks, and the U.S. Forest Service, will be present during all burn activity.