Part of the 2017 burn near Nazko, B.C. Run-off from burned areas contains additional sediment and ash. Melanie Law photo

Ash in water from 2017 wildfires causing decrease in oxygen

“Ecological balance is out of whack,” says biologist with the Fish and Wildlife Branch

The many burned areas from last year’s devastating wildfires will take years to recover, as will any new burn areas from this year.

In the wake of the 2017 wildfires, biologists with the Ministry of Forests, Lands, Natural Resources Operations and Rural Development (FLNRORD) are continuing to monitor the ecological impact of fire throughout the province.

Biologist Mike Ramsay, who works for the Fish and Wildlife Branch in Williams Lake, was the lead on a team of biologists who last fall 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 the perimeter of the wildfires.

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.

At the time, 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because many of the area restrictions that were in place around wildfires in this region had only recently been rescinded.

Eight months later, Ramsay says his team has investigated some rivers and lakes in the region, but a study has yet to be undertaken.

Ramsay says they have gone and looked at certain areas based on requests from the public, but are not fully investigating the matter, as other biologists within the Ministry are examining the long-term effects of the wildfires in depth.

But Ramsay did have some observations about what’s going on in bodies of water in the Cariboo, post-fires.

“This isn’t substantiated, but we have noticed that in some of the rivers around the burned areas there’s more turbidity [water cloudiness caused by large numbers of individual particles], so more erosion coming from some of the areas, especially with the amount of water and rain we’ve had this year,” he notes.

Ramsay explains that burned trees don’t absorb water because they are dead, and the water running off over ash and sediment rather than vegetation means its easier for the run off to pick up more nutrients and carry it into the water.

“Because the lake is breaking down biological nutrients, that process takes up oxygen and makes the lake not have enough oxygen to support fish populations.”

Ramsay says they have noticed some winter kill to fish populations around the region, but says the exact cause is difficult to determine.

“It could have been a longer winter… but in some part it’s due to the fact the run off has taken more nutrients from the exposed soils and had them in those lakes.”

Fire retardant, an often bright red substance which is used to slow or stop the spread of fire, is more abundant in the environment now after the fires.

The BC Wildfire service says last year it used 21 million litres of retardant, which ranks as the second highest usage in B.C.’s history (with 2003 the year that used the most).

But Ramsay says whether or not it is having an effect in lakes and rivers has yet to be fully investigated.

“Whether the retardant also added some nutrients to the lakes… you’re getting farther and farther down a road of assumptions,” he comments.

“In general our lakes are nutient poor or nutrient neutral, so a little bit of nutrients from fire or fire suppression stuff is mainly phospate [which is a component often found in fertilizer], so nutrients from that would have very little impact,” he says.

Overall, Ramsay says that while the turbidity of the water is higher because of the ash, that doesn’t necessarily mean the phenomenon is killing fish.

“Remember that this has always been a fire-dominated ecosystem, so the things that are going on in the large scale of things… we only think of 100 years.

“When you think these fish have been around thousands of years, this is probably something they historically have managed and is more natural than unnatural,” he comments.

“We are going to go through a period where the ecological balance is out of whack. … We are going to get more flash, high flows, we are not going to get water that stays on the land as much. It’s going to take years and years to correct.”

READ MORE: Biologist will be monitoring wildfire impacts on aqua culture and runoff



editor@quesnelobserver.com

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