The NSW Environment Protection Agency has imposed the penalty after it found that in May 2020, Cleanaway Equipment Services Pty failed to notify the authority when the solvent Vivasol 2046 leaked from its Queanbeyan premises into the stormwater system and flowed into the Molonglo River.

Cleanaway has confirmed in a social media post that more than 2500 litres of the solvent entered the river during the two incidents. The company admitted it caused harm to the river for more than two months and affected macroinvertebrates.

Vivasol 2046 is an industrial solvent used for cleaning and is toxic to fish and other aquatic organisms. It is fatal if ingested.

The EPA said the offences occurred on consecutive days on May 14 and 15 2020.

After the spill was detected, Cleanaway installed multiple lines of pollution control on the river and used sucker trucks, which helped limit the spill to a one-kilometre section of the river.

On-ground assessments at the time revealed the spill did not reach the lower reaches of the Molonglo River, Lake Burley Griffin or downstream water users.

However, the authority described it as "a serious incident" and added that the "unnecessary delay in reporting to the EPA contributed to a prolonged impact and clean up by multiple government agencies in NSW and the ACT".

EPA Acting Chief Executive Officer Jacqueleine Moore said that the conviction and fine should send a "clear message that all businesses are accountable to the people of NSW when it comes to protecting the environment".

"It's the duty of all NSW businesses to notify the EPA if their operations threaten or cause harm to the environment," she said.

The penalties include fines of $280,000 and $150,000 for the two pollution of water offences, and $187,500 for the failure to notify.

The court also ordered Cleanaway to pay legal and investigation costs of more than $305,000.

The huge fine comes at the same time as the Labor Party has made an election pledge of $200 million to an Urban Rivers and Catchment Program with Landcare ACT, with a $2.775 million waterways mission across the Ginninderra, Molonglo and Southern ACT catchments.

Cleanaway subsidiary companies have previously been subject to EPA action with a $15,000 fine in November 2020 for alleged waste storage offences at Rutherford and a $1500 fine for alleged poor record keeping at a South Windsor premises.

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