The Environment Protection Authority (EPA) has published its report which was forced by Port Kembla resident Jess Whittaker sampling water in what is known as the Darcy Rd drain, which flows into the harbour.

Ms Whittaker's tests indicated that levels of arsenic, copper, lead, zinc, and other metals which breached water quality guidelines for aquatic ecosystem health.

After sampling two locations on 10 occasions between between November 2020 and September 2021, the EPA has reported elevated levels of certain metals are regularly observed.

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All samples showed levels of selenium and aluminium which were higher than marine guideline values - levels of concentration that trigger environmental concern.

Some samples showed levels of arsenic, manganese and uranium above the guideline values.

Other metals including lead and boron were found at levels below the guidelines.

"Further investigation would be required to determine whether the concentrations of these metals pose a risk to aquatic ecosystem health," the report stated.

Ms Whittaker, a former Greens political candidate, said it was "shocking" it took a citizen to get any action taken from the EPA, but she was pleased with the outcome.

"The process was really good, full credit to the local EPA officers, who involved the community in the sampling to observe," she said.

"I'm really happy that [with] all the businesses who deposit into that drain, it's been gone over with a fine-tooth comb to see what's going in and what can be stopped, and what can be hopefully remediated."

Ms Whittaker was worried the EPA report stated "the presence of contaminants is not unexpected given the long industrial history of the area".

"If it's not unexpected, why hasn't it been actively monitored?" she said. "It's concerning - are there other things like this going on, do we have to look further?"

The EPA identified two industrial sources of pollution to the drain: Port Kembla Copper, which no longer operates industrially other than wastewater treatment, and Ixom, which supplies and recycles sulphuric acid at its acid regeneration plant.

It had been licensed by the EPA to discharge "process water" (water contaminated by industrial operations) into the drain but Ixom has now agreed to cease by November this year.

An Ixom spokesman said it was working with the EPA.

"It is important to acknowledge that Ixom has been fully compliant with its licence requirements regarding the Darcy Road drain since taking over operations at the site in 2015," he said.

"Ixom is pleased its agreement with the EPA will contribute to improving environmental outcomes in the area."

The report found pollutant levels from sampling on days when Ixom discharged into the drain were higher than monitoring reported by Ixom. The EPA concluded that there must be other sources of pollution nearby.

"In addition to the two EPA licensed premises in the Darcy Road drain catchment, there are several industrial and commercial premises for which Wollongong City Council is the environmental regulator," the report stated.

"Some of these sites could be conducting activities that impact on the quality of stormwater, including contributing to elevated metal levels."