The Alberta Energy Regulator has issued an environmental protection order to Syncrude Canada after about 30 blue herons were found dead at the oilsands site in northern Alberta.

The birds were found on Aug. 5 by a worker at Syncrude's Mildred Lake facility, about 40 kilometres north of Fort McMurray.

Bob Curran, director of public affairs with the regulator, said the birds were not found in a tailings pond but in areas called "sumps," low-lying spots on the mine site where surface water collects. Some bitumen was found in that water.

The energy regulator is investigating whether the bitumen was naturally occurring or a result of the plant's operations.

Under the protection order, Syncrude will be required to collect water and soil samples for analysis. The company will also have to develop a wildlife mitigation plan to keep other animals away from where the birds were found.

The company is required to post on its website by 3 p.m. each day information that details "the steps taken in the last 24 hours to remediate impact to the wildlife; and the steps to be taken in the next 24 hours to remediate impacts to wildlife."

The company will be required to submit a final report about the incident and follow-up efforts to the regulator within 30 days of completion of all work required to comply with the order.

"We'll be in contact with them on a regular basis to ensure that the work is moving forward," Curran said. "And once that's complete, then they have 30 days to submit the final report to us."

The energy regulator still doesn't know the exact number of birds that died, Curran said.

Environmental protection orders are "important tools" used to ensure that companies understand exactly what steps the regulator expects them to follow, he said.

"Also, it sets the basis for future enforcement," he said, "if we decide to go down that road as well."

He said that could include "any enforcement action that may be taken against the company, depending on the outcome of our investigation."

Enforcement action, he said, could range "right up to prosecution."

The regulator's officials remain at the site and will stay "as long as necessary," Curran said.

Such orders are issued under sections 113 and 156 of the province's Environmental Protection and Enhancement Act.

"We did find that they were in different stages of decomposition. Some had been dead longer than others. So we want to ensure that we've accounted for all of the fatalities first, and verified that number. Then of course we're looking to determine the cause of death."

Syncrude said Tuesday it is complying with the order and also conducting its own investigation.

"We will continue to work with the Alberta Energy Regulator and Environment Canada to find out what happened," said Syncrude president and CEO Mark Ward said in a statement. "We are saddened by the deaths of these birds. Our focus is now on discovering the cause so we can address it and prevent a future incident."

Five years ago, Syncrude was fined $3 million after 1,600 ducks died after landing on a tailings pond at a different facility in 2008.

Last November, 122 birds were killed after landing in three tailings ponds in the area, including one at Mildred Lake. Curran said that in that case the wildlife deterrents were working properly but severe weather forced the birds to land on the ponds.