Rick Wagner said consultants and contractors working to clean-up the spill in the Slocan Valley are finding dead fish along the shore.
"This isn't just an isolated fish here or two," he said in an interview Sunday.
"It's definitely more fish than we hope to be harmed in something like this," he said. "There's enough there that we're definitely concerned."
Tests must be done to determine if the fish died because of the fuel spill or some other reason, Wagner said, adding that even if the spill is to blame the harmful effects should not last very long.
"What we're seeing is probably a very short, large impact to the fish population. But going forward we're really not anticipating that we're going to see any other effects to fish," he said.
A former resident of the Slocan Valley who visited the affected Lemon Creek on Saturday said he grew up fishing in the area in southern B.C.
"My heart just goes out to all the residents, and I know they're looking for some clarity for a really hard situation," said Sarosha Stockton, adding he's very concerned about other mammals eating the fish.
"There is a small population of river otters that are dear to everyone that lives in the Slocan Valley," he said. "It's really important that people know that these dead fish on the side of river need to be removed."
Stockton visited a pool just downstream of where Lemon Creek meets the Slocan River on Saturday and videotaped some dead fish that had washed ashore, later posting a five-minute clip on YouTube that received widespread attention in the B.C. media.
Wagner says the Calgary-based company responsible for the spill is assessing damage, and may be required to restock the fish population if a significant number died as a result of the crash.
A truck carrying jet fuel for helicopters fighting forest fires crashed into Lemon Creek on Friday.
The potential health and environmental hazards of the spill prompted officials to urge hundreds of people in the area north of Castlegar to leave their homes Friday, but residents were told Saturday they could return.
Stockton said he felt the effects of the jet fuel after filming the video on Saturday.
It "was just nauseating for hours afterwards," he said, adding that his clothes reeked of petrochemicals.
A do-not-use water order remained in effect as of Sunday night, as crews continued to collect fuel pooling in waterways or trapped in log debris.
"It's a very short-lived chemical in the environment," said Wagner. "It dissipates very, very quickly because of heat and the nature of the chemical. So this isn't something that's going to be in that environment for a long, long period."
A spokesperson for the tanker company, Executive Flight Centre, said it appears as if the shoulder of the logging road the truck was driving along gave way, taking the truck down with it.
Wayne Smook, senior vice president, said the company's trucks often need to travel up and down logging roads to transport fuel to vehicles fighting wildfires.
Smook said the crash is extremely regrettable, and the company is doing all it can to mitigate damage.
Smoot said the tanker truck has been removed, and the driver, besides being shaken up, suffered only mild injuries.
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