The Ontario Ministry of Environment and Climate Change continues to look into a flaring incident at Imperial Oil that lit up the Sarnia sky last February.
Ministry spokesman Gary Wheeler says an Environmental Bill of Rights investigation is ongoing and is expected to be complete by the end of this month.
This follows an application that was filed by Aamjiwnaang's Vanessa Gray and Ecojustice Scientist Elaine MacDonald in October.
The ministry could elect to press charges against Imperial, which could result in a fine. They've laid four similar charges against companies since 2013.
On February 23, 2017, the plant lost air supply to several processing units, resulting in three of four on-site flares lighting up.
Photos and video taken from across the St. Clair River in Michigan gave the impression of an inferno at the plant.
There was also a small grass fire along a fenceline between Imperial and ARLANXEO.
At the time, the ministry said air monitoring was conducted and no abnormal contaminant levels were identified.
Wheeler says within 30 days of the completion of the investigation the results will be sent to the individuals who submitted the application and then shared with the general public.