Ruby (1), who has cerebral palsy, relies on the therapy to improve her muscles and for socialisation.
Ms Edwards was upset when told the hydrotherapy supervisor was going on leave.
She was under the impression the classes were cancelled for six weeks.
She appealed to Mandurah MLA David Templeman to help stop the hydro therapy pool from being closed.
Mr Templeman said: ‘Amy contacted my office, I spoke to her on Monday and we arranged for this appalling situation to be highlighted in the media.’
Ms Edwards spoke to the media and the hospital responded that the pool would re-open.
Mr Templeman said that Amy’s story demonstrated the power of taking action to highlight an issue that was not right.
‘I admire Amy’s determination to ensure her daughter and other children continue to have access to the services they need,’ he said.
Acting Director General Professor Bryant Stokes said as a frontline clinical position, the hydrotherapy supervisor position was not affected by the recruitment freeze.
‘Unfortunately, there has been a gap in between the supervisor going on leave and an appropriately qualified staff member commencing in the position last week,’ he said.
The hydrotherapy pool was closed for a week but was re-opened on Friday.