"I know many people travel from out of the district to Ashburton to have their surgery or outpatients appointments."
The theatre building was assessed as part of CDHB's process of reviewing the seismic capacity of buildings.
Mr Meates said 13 patients were affected by the theatre closure today.
"We have managed to reschedule some patients to Christchurch Hospital and the others will be rescheduled to the next available appointment. CDHB staff will endeavour to contact everyone who is booked to have surgery at Ashburton Hospital.
"We will phone those booked this week and write to everyone else.
"We will be making decisions over the next day or so about where Ashburton patients will have their surgery in the short-term."