By Paula Peterson
LAKE TAHOE, Calif./Nev. – Prescribed fires in the Lake Tahoe Basin are much more than a crew going out to an area with a torch to start a fire in the forest. Fuel managers create a plan, or a prescription, to protect a healthy forest from the severity of a forest fire. Prescribed fires are one of the tools used to accomplish the goals, the other being cutting down trees to thin the forest.
Forest managers use fire during less flammable weather conditions in order to keep it within control lines so the fire is of low severity while consuming fuels that would otherwise burn at high severity during dangerous weather.
Most of the current prescribed fires are the burning of hand piles. Crews have gone into the forest and cut down trees, and left them in a pile for future burning. Sometimes the piles sit for two, three, or even four years, waiting for the right time to be burned. The wood in the piles needs to cure so it will burn cleaner and efficiently, leaving as little remnants behind as possible.
Since fire managers never know when conditions will allow them to burn, they need to have piles ready to go at short notice. Piles may stay around longer than planned for the same reason, because conditions weren’t good for a period of time to allow burning.
Once called “controlled burns,” the Forest Service now follows a prescription in order for the operation to be successful, therefore they have changed the name of the events to “prescribed fires.”
The burn prescription determines the environmental conditions necessary for meeting resource objectives in a safe, effective manner. Weather conditions are checked, and re-checked to determine humidity, wind direction, wind speed as well as other variable.
Some smoke now prevents a lot of smoke later should a forest fire hit Lake Tahoe.
USFS Lake Tahoe Basin Management Unit (LTBMU) Fuels Battalion Chief, Phil Heitzke recently answers some questions about thinning forests with fire and by mechanical means:
How many acres were burned last year and how many are planned for this year?
Last (the LTBMU is on a fiscal year, which runs from Oct. 1-Sep 30) year (2020) we burned approximately 515 acres before the pandemic. This fiscal year (2021) we have burned approximately 675 acres on various burn units around the lake, strategically burning units where we can be the most successful. We currently don’t have a set plan for what we are going to burn as this can change due to fuels and weather conditions (both short term and long term).
What is USFS stance on mechanical thinning? Do you plan on more of that?
Mechanical thinning is an important tool for fuels management and the LTBMU plans to continue using mechanical equipment in appropriate areas. However, mechanical equipment can only be used on slopes that are less than 30 percent in steepness. For slopes that are greater than 30 percent, hand thinning is used. This combination of methods helps us accomplish management objectives across the landscape to achieve the desired end result.
Does USFS want to suppress fires or let them burn? Has that changed and what is the current philosophy?
The LTBMU does support suppressing unplanned ignitions when appropriate. At times, naturally occurring wildfires (lightning caused) can be used as a management tool to aid in the natural process of fuels reduction in some areas of the LTBMU.
Is air pollution a concern in Tahoe when planning prescribed fires as much as elsewhere?
Regardless of ignitions, whether planned or unplanned, air pollution is always a concern. We utilize every tool available to us from weather forecasts to smoke modeling to make the best management decisions on when and where to burn to help minimize smoke impacts on communities. Unlike wildfires, we burn under favorable conditions that meet prescription parameters for the best possible outcome.
Who decides what will be burned each year? Does USFS only plan on its land, then Tahoe Douglas Fire, Nevada and California Parks, North Lake Tahoe Fire work on other areas for you?
The Forest Service is a member of the Tahoe Fire and Fuels Team (TFFT) and we work closely with those partners to plan and implement projects that reduce the threat of catastrophic wildfire, protect communities and safeguard the exceptional natural resources of Lake Tahoe. Forest Service crews only burn on National Forest lands and plan for that accordingly.
We do contract out specific units to TFFT members, such as Tahoe Douglas and North Lake Tahoe fire protection districts. Forest Service Fire and Fuels Management staff coordinate closely with our burn bosses, who are actively looking at and assessing various burn units to determine where we can be the most successful with our prescribed burning to best meet management objectives.
Before the burn season begins, we also look closely at what burn units are available and the condition they are in to help prioritize what can be accomplished. With all of the various agencies, cooperators, and stakeholders around the lake, it does take a great deal of coordination and planning to implement lake-wide prescribed fire programs.
If there are multiple agencies doing prescribed burns, do you get together to plan on days so there won’t be too much smoke and activity going on?
We communicate closely with our partners to determine where they may be conducting prescribed burns of their own, so we can minimize the cumulative effects in one area of the lake, if possible. We also closely monitor smoke and weather forecasts and limit our burns to the best of our ability to what the airshed (per Google, an airshed is a part of the atmosphere that behaves in a coherent way with respect to the dispersion of emissions and it typically forms an analytical or management unit) can handle. Prescribed burning is heavily influenced by weather and fuels conditions and some planning occurs only a day or so before ignitions, if the burn window appears to be favorable.
TFFT puts out information whenever a prescribed burn is planned. They have maps and information on their website, https://www.tahoelivingw.ithfire.com/. TFFT was formed in 2008 to implement the Lake Tahoe Basin Multi-Jurisdictional Fuel Reduction and Wildfire Prevention Strategy. Members are a group of dedicated professionals committed to protecting life, property and the environment at Lake Tahoe through proper management of the forests to reduce the threat of catastrophic wildfire, thereby protecting communities, while safeguarding the exceptional natural resources of Lake Tahoe. The TFFT is overseen by a Multi-Agency Coordinating Group which includes the seven Lake Tahoe Basin fire chiefs and nine local agency executives.