Eleven agencies were involved in the Hope Slough spill investigation last month in Chilliwack, but there's still no definitive answer about what caused the sudden fish kill.
Preliminary findings suggest "low oxygen levels" in the historic waterway were to blame for killing thousands of juvenile fish including chum and coho salmon.
The "spilled content" is listed as "unknown" in the spill-response update posted Oct. 18 online from the Ministry of Environment's compliance and environmental enforcement branch.
"The source of the spill in Hope Slough remains undetermined," the report from MOE said. "Multiple factors may have contributed to the fish kill."
It's not expected to impact community health or drinking water.
"This does not usually pose a direct risk to human health," the ministry update said but "the cause of these levels" is still under investigation.
Cheam Enterprises staff Roxanna Kooistra, Sqw谩 councillor Eddie Gardner and Sqw谩 Lands manager Anna-Lise Cooke were the ones who came upon the "devastating and heartbreaking" dead fish on a visit to the upper slough Sept. 23 to conduct routine water sampling.
"The amount of waste discharged was enough to pull the oxygen out of the water, suffocating fish for a three-kilometre stretch that moved downstream for seven days until it dissipated," Kooistra said.
The slough team initially tried to find the source of the spill, activating an emergency response to contain it.
"Cheam First Nation supported federal and provincial agencies in their investigation and are looking to prevent this scale of fish kill and level of contamination from ever happening again," Kooistra said.
The water testing and monitoring is one of several initiatives the nations are working on together to protect water and the Hope Slough system as a sacred resource, and it's how they found the spill evidence.
The water testing is actually part of the restoration project, Shxwlistexw te Sqw谩:la Shxweli: 'Care for the Life Spirit of the Hope Slough' 鈥� a collaborative project between Sqw谩, Shwh谩:y and Xwch铆y貌:m First Nations, funded by Fisheries and Oceans Canada (DFO).
"We believe that this was not a one-time spill but rather an agricultural waste discharge that happens regularly at multiple sites along the slough," said Kooistra.
"Our tests showed levels of fecal coliforms above 20,000 for many kilometres down the slough."
The contamination travelled widely but the MOE's online spill response report of Oct. 3 said that no more stressed or dead fish were found, and that concluded the emergency response phase: "Water quality conditions appear to be returning to typical levels."
MOE's compliance and environmental enforcement branch was on-site investigating several times, according the Oct. 18 update, as well reps with federal Environment and Climate Change Canada who completed their own investigation.
The Fraser Health Authority and the City of Chilliwack identified no risk to drinking water in the area.
The local health authority has been involved since the initial response.
"No immediate health risks have been identified."
The list of agencies involved in the Chilliwack fish kill investigation were listed as follows: Ministry of Environment and Climate Change Strategy, Ministry of Emergency Management and Climate Readiness, Cheam First Nation, City of Chilliwack, Fraser Valley Regional District (FVRD), Cheam Enterprises Inc. (CEI), Environment and Climate Change Canada, First Nations Health Authority, Fraser Health, Provincial Health Services Authority, Health Emergency Management BC.
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