The Scottish papermaker faced charges in contravention of the Pollution Act (1974) at Falkirk Sheriff Court on 7 July.
The discharge was reported to have occurred on two occasions, on 18 September and 30 September 2002, at its mill in Denny, Stirlingshire, and followed warnings from the Scottish Environmental Protection Agency (SEPA) about previous incidents.
In its defence, Inveresk said it had spent 40,000 on rectifying the situation and had also called in environmental consultants.
Falkirk Sheriff Albert Sheehan deferred sentence for three months until 6 October.
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