A spill that dumped billions of gallons of mining wastewater into creeks and lakes this week has led local officials in British Columbia to declare a state of emergency and raised concern for migrating sockeye salmon.

The Cariboo Regional District said the declaration will help it get access to needed resources to protect private property and government infrastructure in the nearby town of Likely, about 248 miles northeast of Vancouver, according to a notice posted today on its emergency operations center Facebook page. It didn't provide further details.

The spill comes as the annual sockeye salmon migration is expected to peak within about two weeks, potentially exposing fish to any chemicals or silt from the spill, according to Craig Orr, executive director of Coquitlam, British Columbia-based Watershed Watch Salmon Society. Effects of the spill on the salmon were still unknown, the department of Fisheries and Oceans Canada said in a statement posted on Twitter yesterday.

"There are a lot of concerns about how all this might affect the life cycle of returning sockeye," Orr said today by telephone. "The timing is particularly bad."

An estimated 2.64 billion gallons of water and 1.19 million gallons of fine sand were released after an Aug. 4 breach of the waste-storage pond at the Mount Polley copper and gold mine, owned by Vancouver-based Imperial Metals Corp. (III) The district is warning people not to drink or use water from lakes and river systems while samples are tested by the provincial Ministry of Environment.

Imperial, which yesterday had its biggest one-day plunge in Toronto trading, said in a statement it didn't know what had caused the breach.

Officials from the British Columbia Ministry of Energy and Mines were at the site probing the cause of the failure, the Canadian Press said, citing Minister Bill Bennett.

Water from the storage pond was "very close to drinking water quality," Imperial President Brian Kynoch told Likely residents at a meeting yesterday, according to the Canadian Press. "The quality, once the solids fall out, should be good. I would drink the water once the solids come out."

Kynoch didn't immediately respond to a request today from Bloomberg for comment.

Imperial fell 0.5 percent to C$10.14 at the close in Toronto. The shares have plunged 40 percent since the spill.

Imperial had to "continuously" raise the height of the storage dam walls to contain rising water from rain and surface drainage, according to Brian Olding, who produced a technical report in 2011 on Mount Polley.

Olding, whose company was hired by two aboriginal groups and Imperial after the company applied for a permit to discharge waste water, said he recommended steps to monitor water coming out of the storage pond, which measures more than 6 square miles. He said he asked at the outset to include a structural review of the dam, but that request was denied.

Imperial was given a discharge permit in 2012, and had applied for a second one before the breach this week, Olding said.

"Obviously there's water pressure on the dam and it's rising," he said. "Common sense just tells you that that is a contributing factor."

The results of water-quality testing by an independent laboratory in Vancouver will probably be available late tomorrow evening, Cariboo Regional District Chairman Al Richmond said today in a telephone interview.

"We're making progress," Richmond said, adding that the district is boosting shipments of drinking water to the area and planning to install portable showers for residents.

Imperial said yesterday the tailings — the materials left over after processing ore to extract valuable metals — were alkaline with an average ph of 8.5 and not acid generating.

"The sockeye are on their way," Olding said. "No one has told the sockeye this is there, so they are just going to find this out as they get closer and closer. No one knows what this is going to do to them."

Fisheries and Oceans Canada said it "will be closely monitoring the salmon run as it approaches the Quesnel system over the coming days." Fishing has been closed in certain parts of the Cariboo and Quesnel rivers.

The tailings pond operated within design limits, Imperial said. Monitoring instruments and workers at the site had no indication of an impending breach.

"It's our responsibility to put this right and we will work diligently to do so," Kynoch said at a news conference broadcast on the BC 1 television.

"Our first priority was, and continues to be, the health and safety of our employees and our neighbors."