While the evacuation orders have been lifted and firefighters and heavy equipment are gone from the area, there are still people on the ground where raging wildfires have scorched forests in the Cariboo-Chilcotin.
Mike Ramsay, a Ministry of Forests, Lands and Natural Resource Operations biologist, noted there are biologists and other experts looking at the extent of the wildfire impacts.
“We won’t know about the impacts of the [retardants and runoff] until next spring. Right now, we’re out there looking to see where we have to prioritize [treatment] next spring.”
He adds this could include reforestation and seeding grass in certain areas.
Ramsay was the lead on a team of biologists who answered some questions about the aftermath of the wildfires and the impacts that retardant and ash might have to the water systems inside and outside of the perimeter of the wildfires during runoff.
Particularly they were asked if the retardant and ash would have an effect on fish and/or the habitat and other animals that consume the water.
The ministry’s fish and wildlife biologists were not able to “fully evaluate the effects of this year’s unprecedented wildfire season on water systems, riparian areas and fish populations in the Cariboo” because many of the area restrictions that were in place around wildfires in this region had only recently been rescinded.
However, the report noted most of the wildfires in the Cariboo this past season occurred in relatively dry ecotypes and few were burning adjacent to riparian areas.
“In areas where fires have occurred, soils can be very unstable and any fire-killed trees can’t absorb water. In those areas, it’s likely that water will run off faster in the spring. “There could be increased erosion and more sediments than usual could be deposited in water systems near those wildfire sites.”
Regarding the fire retardant used by the BC Wildfire Service (BCWS), the biologists said the main chemical ingredient is a fertilizer.
The report noted water-soluble fire retardants are commonly used in fire suppression because of their long-lasting effect on fires. They contain ammonium salts, which affect the burning process of forest fuels.
“Retardants prematurely release the gaseous fuels within logs and debris. This reaction releases a water and carbon dioxide combination that cools and suffocates the fire. “Retardant has a much longer-lasting effect than water in fire suppression because it does not evaporate.”
Nearly 90 per cent of the fire retardant solution is water. The main ingredient in the retardant used by the BCWS is ammonium polyphosphate fertilizer, which is the active fire-retarding component, the report stated.
Fire retardants also contain small quantities (five to 15 per cent) of performance additives.
“The actual retardant components present in the solution are consumed by plant life and provide nutrients to plants. The gum thickener and other inorganic compounds are biodegradable and will break down via other means in the environment.”
Ramsay said if significant amounts of this fertilizer are introduced into a stream or a lake, it could increase nutrient levels and result in faster and denser plant and algae growth than normal.
The impacts of wildfires on riparian areas, bodies of water (such as lakes), fish and other animals typically would not be seen until the following spring’s runoff period, he said, adding if a lake isn’t getting its normal pattern of runoff and oxygen and there is an increase of fertilizer, it could lead to extra blooms of algae.
“Algae is naturally occurring in Interior lakes and it grows to the extent that the nutrients are available. If there is a lot of nutrients, algae will continue to grow and grow and grow.”
If large amounts of this organic matter start to decay in a lake as the summer progresses, that decomposition process uses oxygen and the water body’s oxygen levels can decrease as a result.
If the amount of oxygen in a lake drops significantly, Ramsay said it could affect the health or viability of fish and other animals living in that body of water.
“A lack of oxygen in the water could temporarily ‘kill’ a lake until nutrient and oxygen levels return to normal.”
The conditions in affected lakes would improve over time and the bodies of water would eventually recover, he said.
“We might expect to see a flush of nutrients from the burnt wood and retardants on the ground in the first year going into the lake, but in subsequent years that would be less and less.
“These would likely be partial fish kills. In a wild lake, we would see fish coming back into the lake because they would be upstream and downstream of the lake, or there would be some left in the lake and they would naturally re-populate.
“On a stocked lake, we would restock it again next year.”
He noted if there is significant flows of water in the spring, the ash would also be nutrients that could into the lake.
“If we get torrential rainfall next spring, we’ll see a big influx of nutrients the first year and not as much the next. But if we don’t get huge amount of water flow, then it will be spread out over the next few years.”
“The real risk is the change in what the runoff looks like over the areas over time because a lot of our lakes are dependent on runoff to oxygenate them every year. If the water flow pattern changes, we could see changes in the chemistry of our lakes….
“This fire burned in a normal ecosystem, so I don’t think those algae growths are going to be huge impacts.
“We’re going to see a little bit of fluctuation in nutrients, some changes in flow patterns, and then as soon as the vegetation gets back up, it will probably be back to normal.”
