Yes.
The red and pink retardant firefighters dump on wildfires has been found to be harmful to waterways.
The slurry typically consists of about 85% water, 10% fertilizer that includes ammonium phosphate, and 5% natural thickeners, stabilizers, bactericides, corrosion inhibitors and dyes usually made of iron oxide.
The solution is not considered harmful to humans or land animals but can be acidic and damaging to plants due to its high concentrations of nutrients. Ammonia is toxic in waterways, and the U.S. Forest Service follows guidelines to limit slurry getting dumped into them.
In a lawsuit challenging the U.S. Forest Service’s use of slurry, U.S. District Judge Dana L. Christensen ruled that the Forest Service has conceded that it’s a pollutant. Case law showed “that the direct effects of fire retardant entering a waterway ‘could include, in certain circumstances, lethal and sub-lethal effects in aquatic species,’” wrote Christensen, who serves in the Missoula Division of the Montana District.
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