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What’s in the floodwater? Toxicity of water detailed in recent Abbotsford study

Human and animal fecal matter, oil and gas, asbestos likely leave water highly contaminated
Flood water takes over east Abbotsford Wednesday afternoon, Nov. 17 (Aaron Hinks photo)

Abbotsford officials have continually issued warnings to stay out of floodwater swamping Sumas Prairie, and a recent City of Abbotsford impact study shows why.

The water pouring across the U.S. border and overwhelming rural farms is likely highly contaminated with human and animal waste, asbestos fibres and oil and gas, according to the study.

Shortly after evacuation orders were issued, Abbotsford Police Chief Mark Serr expressed frustration with people using kayaks to explore the floodplains.

“This water is not safe. This is toxic water that has been leaching in from all different areas,” Serr said, adding a full assessment has not been done yet. “You wouldn’t want your kids … swimming or wading in it.”

All of the rescue teams currently go through a decontamination process when finishing a shift and wear dry suits for protection, said Abbotsford Fire Chief Darren Lee.

“People were asking what’s in (the water), and the true answer is we don’t know, and that’s localized,” Lee said.

The city was provided a $250,000 grant by the federal and provincial governments to create the Nooksack River Overflow Flood Mitigation Plan, which was completed in 2020. It includes an analysis of the potential environmental impacts.

Homes and farms in agricultural areas typically rely on septic systems for sewage treatment, with many also containing lagoons to treat liquid animal waste, all of which are vulnerable to flooding, according to the analysis

The likely result is a biological stew of human and animal fecal matter, and other potential pathogenic microorganisms spreading through the floodwaters.

The analysis cites a U.S. research study that indicated this type of contamination can hang around in soil for years if animal-waste lagoons breach.

Mayor Henry Braun has said there are 20,000 head of cattle on Sumas Prairie, and all the farms have manure pits.

“With five feet of water there’s been saturation,” Braun said. “There’s issues there.”

Crops in the area will need to be assessed for toxicity, the city’s analysis suggests, but biological contaminants will naturally degrade over time.

There is also the potential for longer-term contamination to soils and surfaces from oil and gas.

While there are no gas stations directly in the flooded area in Abbotsford, aerial footage taken in the U.S. shows the water has overtaken some pumps.

Some Abbotsford farms also likely contain oil and diesel-fuel tanks on site, and both above and below-ground types can leak from piping ruptures.

This type of contamination from hydrocarbon sources causes cancer to humans, and is harmful to plants and animals.

Whatcom County Health put out a warning on social media on Nov. 18 that floodwaters from Swift Creek in the U.S., and Sumas River carries naturally occurring asbestos.

“You may have been exposed to asbestos in floodwater, or in mud or sediment left behind.”

This asbestos would likely flow into Canada and be deposited into the flooded areas, the city’s analysis states.

The potential health impacts of naturally occurring asbestos is difficult to assess as most health studies relate to exposure to commercial asbestos products, according to the analysis.

All of the elements combined leave the water with the potential to affect groundwater sources and wells. While wells containing biological contaminants can be disinfected with chemicals, oil and gas is more of a challenge.

The city’s analysis says there are 325 wells (102 designated as water-supply wells) in the area that would be affected by a 200-year flood event where the Nooksack River overflowed and dikes were breached.

RELATED: Levee to be built in Abbotsford to hold back surging floodwaters from Highway 1


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The city’s analysis says there are 325 wells (102 designated as water-supply wells) in the area that would be affected by a 200-year flood event. Image from the Nooksack River Overflow Flood Mitigation Plan.
A screenshot from an aerial video of the flooding in Washington show an gas station overtaken by floodwater.