Post-Wildfire Water Quality Concerns FAQ
Q: What are the toxins in the environment after the fire?
A: Fire ash contains microscopic particles (dust, dirt, soot) that can be deposited on indoor and outdoor surfaces and can also be inhaled if the ash becomes airborne. Unless tested, the ash is not classified as a hazardous waste, however it may contain traces of hazardous chemicals such as metals (lead, cadmium, nickel, and arsenic), asbestos (from older homes or other buildings), perfluorochemicals (from degradation of non-stick cookware), flame retardants and other caustic materials. For these reasons, it is advisable to be cautious and avoid any unnecessary exposure to the ash.
Q: Will the toxins in the environment make me sick?
A: Fire ash may be irritating to the skin, nose, and throat and may cause coughing and/or nose bleeds. Fine particles can be inhaled deeply into lungs and may aggravate asthma and make it difficult to breathe. If the ash contains asbestos, nickel, arsenic or cadmium, then exposure is a particular concern because these substances are known carcinogens. Because the substances in the ash vary, it is always best to be cautious.
Q: What precautions should be taken in and around the fire ash environment?
A: When cleaning areas remember to control, contain, and capture ash. Use appropriate protective wear. Don’t use leaf blowers or hoses to remove ash and debris. Sweep gently with push brooms, bag ash and debris, and place into trash can. Some areas can be cleaned with a mop and broom. When vacuuming avoid standard shop vacuums and instead use household vacuums or vacuums equipped with HEPA filters. More information: Ventura County Public Health and Air Pollution Control District Health Notice.
Q: What is being done to prevent ash and other toxins from impacting water quality?
A: Local agencies are working together to develop management strategies to reduce transport of ash and other toxins from entering the storm drain system. The goal this winter is to prevent ash and debris from burned structures from entering local waterways.
Post-Wildfire Sediment and Erosion Control FAQ
Q: What causes soil erosion in burned areas, or downstream of burned areas?
A: When active fire ends it leaves behind bare dirt or decreased vegetative cover. Because of the loss of vegetation, the top layer of soil becomes loosened, making it vulnerable to increased runoff, erosion and sedimentation.
Q: What can property owners do to manage erosion and debris impacts and minimize the risks of erosion?
A: Property owners can implement erosion and sediment stabilization practices to keep sediment and debris from impacting homes. Erosion and sediment stabilization techniques such as gravel or sand bags, hay bales, silt fences, straw wattles, log erosion barriers, and mulch around burned areas can be effectively used to reduce the chances of ashes and other material from mobilizing during rain events. More information is available here.
Q: Where can I find additional resources on how to protect my property from erosion after the fire?
A: The United States Department of Agriculture (USDA), Natural Resources Conservation Services (NRCS) provides information and resources here.
Q: What is being done to prevent erosion and harmful runoff from impacting our watershed?
A: Local agencies are working together to assess and develop management plans to reduce sedimentation and flooding impacts in fire-impacted areas.
Q: What is a “hazard tree” and how should it be removed?
A: It is a fire-damaged tree which is dead and would pose a threat to the safety of the public and infrastructure if it should fall. Also, insect infestations in the burned trees are a hazard. More information is available here.
Q: What are some techniques to control erosion after the fire?
A: The following are some ways of treating and preparing the soil to help control erosion.
- Hand Raking
Hand raking is a treatment for prepping the ground for mulching after the fire. A detailed description is available here.
- Contour Sandbags
Sandbags placed along contour of slope to increase infiltration, reduce erosion, and help contain soil on slopes. A detailed description is available here.
- Erosion Control Mats
Erosion control mats are protective mulch blankets or stabilization mats anchored to slopes to limit erosion and enhance revegetation. A detailed description is available here.
Hydromulching is the practice of placing a mixture of water, fiber mulch and tackifier on burned slopes to prevent soil erosion. Please refer to the fact sheet from NRCS for detailed technical information.
Q: What are some types of barriers that can be used to stop or contain sediment and water flow?
A: The following are some types of barriers which can prevent sediment and water flow.
- Sandbag Barriers
The use of sandbag barriers is one of the post-fire erosion and sediment stabilization practices to keep sediment and debris from impacting homes and downstream waterways. Please refer to the fact sheet from NRCS for detailed technical information.
- Log Erosion Barriers
Logs placed on the contour perpendicular to the direction of the slope provide barriers to runoff from heavy rainstorms, and are called log erosion barriers. Please refer to the fact sheet from NRCS for technical details.
- Straw Wattles
Straw wattles are long tubes of plastic netting packed with straw. Wattles are used in a similar fashion to log erosion barriers. The wattle is flexible enough to bend to the contour of the slope. They are generally available from home improvement stores.