September 2026 Prescribed Burn FAQ
Angel Island Prescribed Burn FAQ’s - Posted 09/25/2026
Why are you conducting a prescribed burn here, especially when there is no wildfire threat to any mainland portions of the greater Bay Area?
These burns were conducted as a part of California State Parks Prescribed Burn Program and funded by the Proposition 4 Climate Bond. The burns were intended to reduce the severity of future wildfires on the island, protecting the island’s historic structures, visitors, and ecological values. Prescribed burns support ongoing vegetation management, wildlife habitat improvement, invasive plant management and other long term stewardship efforts at the park. These burns were specifically aimed at reducing fuel loads in oak woodland areas as well as preserving grasslands and coastal scrub on the island from encroachment by invasive plants and native tree species.
What has been done to address the wildfire risk and fuel loading on Angel Island beyond these recent burns?
State Parks has worked to reduce fire risk and preserve the island’s biodiversity since the establishment of Angel Island as a State Park in the late 1950s, often with support from fire agency partners. Prescribed burns are one of multiple tools State Parks uses to reduce wildfire risk and support the stewardship of Angel Island. The September 2026 broadcast burns were the first in recent years, with pile burning having occurred annualy since 2020.
Other ongoing efforts include hand removal of invasive plants across hundreds of acres on the island annually by parks staff, contractors and volunteers, manual and mechanical fuel reduction around park structures, the use of air curtain burners to remove accumulated larger down trees and the beneficial re-use of dead fall to provide firewood for living history programs and other park operations. More Information about this work can be found on the park website.
Grazing animals can consume grasses and small plants but would not help reduce down dead logs and leaf litter, two primary objectives of these burns. Deer browse and grazing on the island generally reduces these fuels. This combination of factors and significant logistical challenges limit the potential effectiveness of goat, sheep or cattle grazing on the island to meet many objectives of these burns.
Has a prescribed burn ever been conducted on Angel Island?
State Parks has previously conducted prescribed burns at Angel Island State Park, although broadcast burns have not occurred since the mid-1990s and early 2000s. The Angel Fire wildfire occurred in 2008, and fuels have been accumulating since then. Pile burning has been implemented multiple times since 2021 with support from Marin County Fire. These burns are being timed to return broadcast fire at an interval that will help to reduce the risk of a high intensity fire if we were to wait until the next uncontrolled wildfire.
What about the smoke impacts that were felt in populated areas across the Bay Area?
The prescribed burn was planned and coordinated with the Bay Area Air District to minimize smoke impacts on surrounding communities. A smoke management plan for this project was approved by the Bay Area Air District. Burns only proceeded with Air District approval. There are significant smoke sensitive receptors in all directions surrounding the island which have been taken into consideration. Below is a list of populated areas the burn planners sought to avoid or minimize impacts to:
- Tiburon – 1.6 miles northwest
- Sausalito – 2.6 miles west
- San Francisco – 3.0 miles south
- Mill Valley – 6.0 miles west/northwest
- Corte Madera/Larkspur – 6.3 miles northwest
- San Rafael – 8.9 miles north/northwest
- East Bay cities ranging from Richmond, 5.8 miles northeast, to Oakland, 7.8 miles southeast, and Berkeley, Albany, El Cerrito and multiple other communities adjacent to these areas.
Wind direction and nighttime air flow ultimately determined which area experienced the most significant smoke impacts. The Bay Area Air District stipulated that a mixing height of at least 500 feet above ground level must be present during the burns.
Burn planners worked closely with Air District staff to attempt to conduct the burns as early in the day as possible with the intent that smoke rose above the island before dispersing aloft into the afternoon. On both burn dates, this outcome generally held throughout the morning hours; however, smoke conditions shifted in the afternoon as onshore winds began to materialize, decreasing the height of the smoke and impacting communities, primarily in the eastern Bay Area.
With all the fires in California, why are you exposing us to more smoke with prescribed burns?
Prescribed fire smoke generally has a significantly less of an impact than wildfire smoke. By conducting short duration prescribed burns we considerably reduce hazardous fuels that are a large contributor to catastrophic wildfires. We do extensive planning and coordination before and during these burns to minimize potential impacts. The short duration (hours) associated with impacts of prescribed fire smoke compared to long-term (multiple days) effects of uncontrolled wildfire is a critical component we evaluate during these projects.
Why did the burns occur on warm days?
Prescribed burns can only occur on days when vegetation is dry enough to support fire spread within the designated burn area. The number of warm days on the island is incredibly limited each year given its location. Burning under wet, foggy or cool conditions decreases combustion, potentially increasing smoke outputs and preventing the burns from meeting objectives. Climate modeling and historical records analysis done ahead of burn implementation indicated few suitable times that these burns could occur, all of which were in the late summer/early fall.
What is being done to protect the historic buildings on the island?
California State Parks has done substantial work on Angel Island to protect structures from fire. Defensible space work has been done around historic buildings as well as park facilities and residences. That work is supported through the California State Parks Facility Ignition Prevention Program (FIPP).
What considerations are being made for wildlife on the island?
Prescribed fire improves wildlife habitats by clearing dead brush, recycling soil nutrients, and creating a diverse landscape that provides animals with better natural forage, shelter, and safety.
These burns are planned to occur outside migratory bird nesting season, with species specific surveys occurring ahead of burns taking place. During prescribed burn operations, agencies used low-intensity ignition patterns to allow animals to escape safely while improving long-term ecosystem health.
Did the park have any closures during the prescribed burn?
Angel Island State Park remained open during burn days. However, some trails and roads near the burn areas were temporarily closed during and immediately after burns to protect visitor safety.
How long will this prescribed fire last?
Ignitions occurred over two days, with burn down occurring for 1-4 days following ignitions within the interior of the units, conditions and staffing permitting. The project is broken up into 7 different plots totaling 260 acres to be treated with broadcast burning. 147 acres were treated over the two days this month. There is no immediate plan to continue burning.
Angel Island Wildfire History:
On Oct. 12, 2008, a wildfire burned accross half of the island, filling much of the Bay Area with smoke. It was human-caused and burned across the southern half of Angel Island. Historic buildings on the island were protected and fortunately survived the wildfire. Driven by easterly winds, heavy overgrown vegetation and steep hillsides, the fire consumed 380 of the island’s 731 acres.
A cadre of ferries and two military-type landing craft delivered more than a dozen fire engines and another 275 fire personnel to attack the blaze after it was first reported at 8:30 p.m. Sunday. There have been multiple smaller vegetation fires on the island over the past 25 years, ranging in size from less than one acre to four acres.
About the Island:
Angel Island State Park offers some of the best views of the surrounding Bay Area. At 731 acres, Angel Island is the largest natural island in the San Francisco Bay. The islands highest point is Mount Livermore at 788 feet. There are over 120 buildings on the island, many of which are historic. With great hiking trails and many other recreational opportunities readily available, Angel Island is truly a hidden gem in the midst of the urban Bay Area.
Beginning with the earliest inhabitants, the Coast Miwok, have stewarded this land since time immemorial and still retain a close connection with the island to this day. When early Spanish explorers like Juan Manuel de Ayala (one of the first Europeans to map the San Francisco Bay) visited the Bay they would use the island for supply stops.
Starting from the Civil War at Camp Reynolds to the Cold War at the fenced remnants of the Nike missile site, Angel Island also has nearly 100 years of military history. Through World War I and World War II, thousands of returning and embarking troops were processed at Fort McDowell.
From 1910 to 1940, the U.S. Immigration Station on Angel Island processed hundreds of thousands of immigrants, the majority from China due to the Chinese Exclusion Act of 1882. During WWII, Japanese and German prisoners of war (POWs) were detained at the Station before being sent to facilities farther inland.
In 1954, the transition of Angel Island to a California State Park began. Starting with Ayala Cove on the western side of the Island, park visitors had the first opportunities to enjoy the beauty of this amazing Island. In the early 1960's, the final departure of the military allowed the rest of Angel Island to become park lands and the rest is history!
“Angel Island is one of the most historic sites on the West Coast that goes back to the Civil War,” said Roy Stearns, retired deputy director of California State Parks. “In 1863 they built Camp Reynolds and all the buildings that are left are from that era and were meant to guard the bay during the Civil War. It was an immigration station, the Ellis Island of the West. There was also a Nike missile site here during the Cold War. Before that it was inhabited by Indian tribes. The island is steeped in an amazing amount of history. To lose that would have been tragic.”