Wildfire and Water Quality

Fire Retardant and Water Quality

Firefighting agencies use a variety of materials as fire retardants for air-drop (the reddish substance that you see coming from planes, and that might be left on the landscapes and structures within or near the burned area). Most fire retardants have the same active ingredient: phosphorous. Phosphorous is one of the building blocks of plant life, so it can be taken up by plants surviving the fire. The phosphorous that is not taken up by plants on the landscape may become mobile in the first few rainfall events, and make its way to the nearest waterbody in runoff. While it is possible that this compound can contribute to eutrophication (when a body of water becomes overly enriched with minerals and nutrients that induce excessive growth of plants and algae), it is more likely that precipitation associated with the wet season will result in the phosphorous being pushed out to larger water systems and diluted with the greater quantities of water present in those systems.

• More information on the USFS fire retardant systems is available here: on the Forest Service National Technology and Development Program's Product Information page.


• More information on the CAL FIRE, fire retardant system is available on CAL FIRE's Aviation Program page.

Fire Effects on Drinking Water

If your drinking water comes from your own private well, some signs your water supply may have been impacted by wildfires include:

• Changes in water appearance, clarity, color, smell and/or taste, or
• Power outages affecting your system or fire damage to system structures (e.g. building, water intake valve, water well head, treatment system, piping, etc.), which may interrupt normal treatment practices or cause a loss in water pressure. This could allow pollution to enter the system or lead to stagnant water lines that may need to be flushed.

Specific questions regarding your drinking water source, including wells, should be directed to your water purveyor or the State Water Board’s Division of Drinking Water.

• State Water Board's Division of Drinking Water

Springs Appearing in Burned Areas

In some places, the landscape’s post-fire response might include the appearance of springs. There are significant anecdotal accounts of this happening throughout California, though limited research has been done on the topic. The science behind this comes from simple biology and physics: plants of all types pull water from the soil, and usually larger plants pull water from deeper in the soil profile. This process is known as evapotranspiration. When those plants disappear – either from fire, land management activities, or even from animal browsing – the water that would otherwise be pulled up by plants is left to follow another cycle. In many cases, the water in the soil accumulates to the point where the groundwater level rises above the ground surface, creating pressure to release the water from the soil profile and onto the surface of the land, forming a spring. Depending on the landscape, the spring may last only a season or two, or it might last multiple years. As the vegetation cover returns, the spring flow might lessen or even disappear altogether. It is important to remember that springs remain waters of the state; it is California law that you must get a permit to use spring water, even if the spring is temporary.

Addressing Fire Lines

The emergency nature of firefighting means that actions are taken to address the primary goals of protecting key values at risk (including homes and other important infrastructure) and ultimately putting out the fire. Out of necessity, these actions are often taken without considering other management objectives, such as watershed protection or erosional risk. Fire suppression repair and rehabilitation is the repair of damage caused directly from fire suppression activities, such as these dozer-created fire lines. It is not the repair of areas damaged by the fire; just the damage caused by fighting the fire. The authority to complete suppression repair work lies with the Public Resources Code (PRC), including PRC 4675 and 4676 at the California Legislative Information page.

CAL FIRE is the point state agency in developing fire-specific suppression repair and rehabilitation plans for each wildland fire on non-federal lands. Generally speaking, CAL FIRE’s policy is to install waterbreaks/waterbars on all fire lines, including both hand lines and dozer lines. This is generally done during mop-up, following an area being burned, and NOT if the activity will negatively affect active suppression activities. If there are fire lines among structures, waterbars will be installed with hand crews to minimize the impacts on residents and the residential area.

Fire suppression repair and rehabilitation activities may also include efforts to restore infrastructure damaged by fire suppression (again, not to repair infrastructure damaged by the actual fire). This may include fence repair, the restoration of berms/barriers on roads, drainage at ditch or watercourse crossings, etc. Special attention is given to suppression activity restoration in watercourses, including the removal of all slash, soil, and debris deposited during firefighting, and pulling away and stabilizing loose soil. Local slash or mulch will only be used in the case where it is either not flammable OR where the fire is adequately controlled so that the fire line won’t be compromised by the restoration activity.

If it appears that an erosional risk exists from fire suppression activity that has not been addressed, please contact your local CAL FIRE unit or regional office.

Swimming in Affected Waterways and Waterbodies

If a reservoir or recreational lake is managed by a local, state, or federal agency, such as a local park, State Parks, or the National Parks Service, you can contact that agency for up-to-date information regarding the resource. If you are interested in swimming in an unmanaged waterway, such as a river or stream, it is best to be conservative; if the water is muddy or otherwise turbid, swimming is probably not a good idea. If the water is clear, it may still be impacted by the compounds mobilized by the fire/fire suppression/rain events, and more information might be available through calling the appropriate Central Valley Water Board office or your local water purveyor.

How will the fire affect general water quality? How will our rivers, streams, and lakes be affected in the short and long-term?

Before the rainy season begins, water bodies may have already been affected by ash-fall transporting organic and/or chemical contaminants. Usually the most serious negative effects on our local waterways occur once the rainy season begins. Heavy rain events will cause runoff, carrying ash, chemicals, and sediment into surface waters likely causing very turbid waters and sediment deposition. This is a normal annual occurrence, which is referred to as the “first flush”, this rain event often brings with it accumulated road grime, organics from landscaping and natural leaf-fall, and other elements that accumulate throughout our dry season. The first flush effects will be exacerbated, however, with the addition of a widespread fire, and may have significant deleterious effects on riparian habitat, especially for anadromous salmonids and other sensitive aquatic species.

Despite post-fire efforts to mitigate higher-than-natural erosion rates, turbidity in local waterways will likely be high with the first rain event and continue throughout the wet season. While research indicates these elevated turbidity rates decline with time, they can remain higher than the normal background (unburned) rates for up to 10 years following a fire (see the USFS Pacific Southwest Research Station's Fire Science Post-fire erosion page for more information.)

What should I do with my dirty pool/spa water?

Your pool water may be contaminated with ash, fire retardant, or other solids or liquids from a burned structure or fire suppression activities. Releasing this water could negatively impact surface waters through transport of those contaminants and from erosion caused by the actual release. Pools may not be drained to the street gutter, storm drain, or to any surface water body or in a manner that results in pool water reaching surface waters via overland or concentrated flow.

Your local land use jurisdiction (city or county) may require an inspection prior to pool draining. Call the city environmental health department, or your local equivalent, to determine any special requirements prior to addressing your contaminated pool water. In addition, pool cleaning companies may be good resources for information and for assistance in addressing the issue.

Information Regarding Post-Fire Assessments

If a fire burns on federal lands (BLM, NPS, or USFS, among others), the federal agencies will generally identify and assign a team of scientists to complete a Burned Area Emergency Response (BAER) evaluation. This is completed to ascertain specific threats to human life, property, cultural resources, and/or environmental and habitat values. Information on the BAER program can be found at the U.S. Forest Service website. BAER reports specific to individual fires may be found on the federal government’s Incident Information System (InciWeb).

Fires that burn on non-federal land, including private, state, and local jurisdiction landscapes, will be assessed by a Watershed Emergency Response Team (WERT) led by CAL FIRE, composed of state experts, and shared via a WERT report for each individual incident. The objective of the WERT report is similar to that of the BAER team, including identifying risks to values in/on the burned landscape. More information on the process can be found in the CAL FIRE: WERT and Post-Fire Watershed Restoration/Recovery presentation or do an internet search for “WERT” and the specific fire in which you’re interested to find the WERT report for that fire.

Post-Fire Timber Harvesting, Hazard Tree Removal and Debris Flows

Landowners may choose to harvest damaged merchantable timber shortly after the fire in order to salvage the value of the trees (typically conifers) before they degrade. In order to harvest timber for sale, barter or trade, the landowner will need to obtain the appropriate permit or exemption notice through CAL FIRE's Forest Practice section. Impacts to the environment from wildfires can be significant, especially relative to the health of streams, rivers, and wetlands. Following a wildfire, the landscape is exceptionally vulnerable to impacts from land use activities. While conducting timber salvage operations, landowners and their consulting registered professional foresters and licensed timber operators must be aware of all regulations that apply to their activities and ensure that operations are conducted in a manner that is protective of the environment, including water quality. Additional permitting through the Central Valley Water Board may be required for such projects.

Trees burned or damaged by wildfire along roadways or utility lines or around other structures may pose a significant safety threat, these are frequently referred to as "hazard trees". Removal of hazard trees may be necessary to protect infrastructure, however, such operations can represent an elevated risk to the environment and particularly to water quality without adequate consideration for timing of operations and proper installation of erosion and sediment control measures.

Wildfires also increase the risk of debris flows, hazardous flows of rock, sediment and water that travel down hillsides and into adjacent valleys. Debris flows can be extremely dangerous and pose a risk to human health and safety, and can do serious damage to infrastructure. It is not uncommon for localized debris flows to block watercourse crossings and cause catastrophic failure, leaving roads unsafe and even unpassable. More information available through the California Department of Conservation's Geological Survey site.