The Central North, Upper Derwent and the Midlands are trending towards extreme dry conditions, a parliamentary committee has heard.
"That will need to be monitored carefully, on a weekly basis," said Primary Industries Minister Guy Barnett.
Mr Barnett told the government business enterprise scrutiny hearing of Tasmanian Irrigation on Wednesday he did not declare extreme dry conditions in the South-East on the advice of TI and TasWater, despite water restrictions being recently imposed on irrigators in the area.
"There are certain triggers that are considered ... as to whether that is triggered or not," Mr Barnett said.
"In certain circumstances, of course these are enacted to ensure best outcomes for the community and farmers."
After having their water use halved, farmers using the South-East Irrigation Scheme will see water restrictions eased on Friday.
"There has been a stabilisation and recovery of the water," Mr Barnett said.
TI chief executive Andrew Kneebone said those utilising the Stage 3 tranche will see their access increase to 70 to 80 per cent.