The company reported the discharge of 1.2 megalitres of effluent, containing concentrations of arsenic above environmental protection licence limits, at 3pm today.

The NSW Office of Environment and Heritage said the discharge occurred this morning.

"The Office of Environment and Heritage has begun an investigation into the incident, ordering Orica to provide a full and thorough report to OEH as soon as possible,’’ a spokesperson said.

Full report in tomorrow's Newcastle Herald.

Click on the image above for a slideshow of images charting the Herald's pictorial coverage of this story.

Listen to Newcastle Herald environment reporter Matt Kelly's interview with international environmental activist Erin Brockovich.

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