Initial water quality tests in Gladstone Harbour have found no detectable levels of cyanide after Orica notified the EPA of chemical leaks.
Earlier this month the explosives manufacturer came under investigation after it reported a number of wastewater discharges containing higher than licenced levels of cyanide.
It is currently licenced to discharge waste container one milligram of total cyanide per litre of water.
However Orica notified the Department is had carried out a number of discharges since January of around 2 milligrams per litre.
It went on to state that it is not currently exceeding the limit and the last incident on 22 February.
The QLD Department of Environment and Resource Management have now carried out testing, the Gladstone Observer reported.
"Cyanide was not detected in water quality samples taken near the Orica discharge point on Friday," DERM director general Jim Reeves said.
"The detectable limit for cyanide is 0.004 milligrams per litre (mg/l).
"Further results from samples taken on Thursday and Friday will be available later this week," he said.
Reeves added that DERM is carrying out additional investigations for other non-compliant releases.
"DERM officers are onsite at Orica to monitor and ensure compliance prior to approving any discharge from the Orica cyanide plant."
Early last year traces of cyanide were also found in the city’s stormwater drains near the Orica plant.
According to a spokesperson for the Department of Environment and Resource Management, the breach was not uncovered by Orica reporting it, but rather through proactive compliance checks by the department.
"Initial investigations by DERM officers indicted there was no risk to the environment or public," a spokesperson said at the time.
"The department takes incidents like this very seriously and if the investigation finds an offence has occurred, the department will take appropriate enforcement action."
If Orica is convicted of causing environmental harm with this most recent leak it could face fines of more than $2 million.