FOUR mines are under investigation for potential breaches of environmental rules about discharging contaminated water into the Fitzroy catchment.
The Queensland Government says six mines - Curragh, Minerva, Saraji, Hail Creek, Moorvale and Burton - are currently pumping under approvals.
But the department responsible for the Fitzroy Basin's independent water quality monitoring program has launched an inquiry into compliance matters at Peak Downs, Capcoal's German Creek, Cook Mine and Callide Mine.
The potential breaches at Callide include failure to notify the authorities, exceeding the electrical conductivity limit and insufficient dilution in the receiving environment.
The news comes as salinity levels in Rockhampton's drinking water continue to rise after the flood which peaked in the city on March 31.
Water at the Fitzroy Barrage normally has an electrical conductivity of 180 Micro Siemens per cm.
Over the weekend it averaged 294, but with elevated levels in the Dawson, Comet, Nogoa, Isaac, Connors and Mackenzie rivers, the saltiness of the region's tap water is likely to increase in coming weeks.
Mines badly affected by the late season rains last month are expected to be pumping for a considerable time.
Peabody Energy has reported it expects its Moorvale Mine to be releasing mine water for 68 days while the Minerva Mine will be pumping into Sandhurst Creek for 50 days and Curragh Mine is expected to be releasing into the Mackenzie River for 40 days.
According to Australian Drinking Water Standards, water is considered "good" for drinking up to 900 Micro Siemens and becomes undrinkable only when it hits 1800.