Pasminco has been cautioned by the Environmental Protection Authority after it was found breaching its licencing conditions at the former Cockle Creek Smelter.
The land is currently being remediated at Boolaroo where the EPA has placed strict limits regarding water on the site.
Twice last year, Pasminco was found to have exceeded its zinc concentration limit.
EPA Hunter Region Manager Adam Gilligan says Pasminoc's actions will be held to account.
"We've taken action, not only to fine them but also to require improvements on site to prevent this from happening again".
"It's also pleasing in this case to see that Pasminco have taken our advice on board"
Pasminco have been issued two $1 500 penalty notices with the EPA saying the offenses pre-date the increase of the penalty notice to $15 000.
