Const. Ian MacDonald said police call-outs since May for such medical emergencies have increased by 39 per cent, resulting in eight overdoses and one death.
Officers on the front line were told to watch for bad drugs and that translated to a number of stories from drug users on the street, he said.
"They started to detail sort of strange reactions to heroin specifically, that they thought there was an extra-potent heroin out there. The heroin was looking different than past product, it had a more grainy kind of consistency and some of them were reacting quite badly to it."
MacDonald said officers started asking questions when the provincial health officer issued a warning in May about 23 deaths related to the opioid fentanyl, which was being sold to heroin users.
The warning said fentanyl presented a significantly higher risk of overdose and was the cause of an epidemic of deaths in Chicago in 2006 where 342 people died.
Tests on a drug sample have yet to be completed, so MacDonald couldn't say if any of the most recent overdoses were caused by fentanyl.
The BC Coroners Service issued a statement shortly after police sent out the warning reiterating that Monteith's death was caused by a mixture of heroin and alcohol.
"Toxicology results did not indicate any presence of the drug fentanyl," the release said.
Monteith was found dead in his Vancouver hotel room on Saturday. Police said it was apparent from the start of their investigation that drugs were likely involved in the Canadian actor's death.
MacDonald said there's no proof that fentanyl caused the overdoses in Abbotsford either because screening tests on a sample they found haven't been completed.
He said police chose to issue the warning because officers were concerned more could die.
"Whether it's fentanyl or not, we are seeing an increase of overdoses to people who use heroin in Abbotsford."
B.C. Attorney General Suzanne Anton said while health professionals and police who deal with street drug users try to help, it's dangerous to take street drugs.
"Of course, it almost goes without saying that when you use street drugs you don't know what you're using and you don't know what it's going to do to you," said Anton.
The minister wouldn't comment on concerns that Vancouver police are not trying to find the dealer who provided Monteith with the heroin that contributed to his death.
"I would have to leave that to the police," Anton said.
MacDonald said police in Abbotsford are having a difficult time pinpointing where the bad drugs are coming from.
He said the bad drugs appear to be part of a larger supply, but there's no evidence that a new supplier has come to town.
"I'm very hesitant to say this is an Abbotsford problem. We're not the heroin capital of the Lower Mainland."
He said police know drug dealers and suppliers go where the money is, and that they are likely spreading their product over the Lower Mainland.
"I think it would be naive to think its staying within the confines of our jurisdictional boundary."
-- By Terri Theodore in Vancouver