The Capital Health District Health Authority says health services would begin to be disrupted as the April 3 strike date draws closer.
While Capital Health has contingency plans in place, spokesman John Gillis says patient care will be affected if the talks last more than a week.
"We need to begin postponing things ahead of an actual strike so that we're not in a position where we have people in hospital without the appropriate level of staff to care for them," he said.
"I would expect to see that into the second week of that countdown period."
The nurses primarily work at four places in the Halifax area: the QEII Health Sciences Centre, Nova Scotia Hospital, East Coast Forensic Hospital and Public Health Services.
Gillis said Local 97 of the Nova Scotia Government and General Employees Union has agreed to maintain full staffing levels for certain services, including the QEII emergency department, dialysis unit, Nova Scotia Cancer Centre, veterans services and intensive care units.
In the event of a strike, staffing levels would drop to an average of 10 per cent for 150 other health service areas, causing major disruptions.
"It ranges from zero in some areas to up to 50 per cent," Gillis said, referring to the fact that some services would have up to half the usual number of staff available.
Gillis said other district health authorities and the IWK Health Centre in Halifax are preparing to lend a hand if there is a strike.
A union spokeswoman said mediation talks led by lawyer Bruce Outhouse were being held at a local hotel.
The president of the union, Joan Jessome, couldn't be reached for comment Friday. A spokeswoman said the union would maintain a media blackout as long as the talks continued.
The talks started a day after Capital Health said it would take legal action if its nurses opt for mass resignations in the event they are legislated back to work by the provincial government.
The warning came from Capital Health CEO Chris Power, who said the authority had learned that union staff, executive members and bargaining committee members approved the idea of mass resignations at a meeting earlier this week.
Power said such a move could lead to "potentially catastrophic consequences to public safety."
Premier Stephen McNeil has said he can't believe nurses would threaten patient safety by resigning en masse to back contract demands.
The health authority has pointed out that under the nurses' contract, they must provide two weeks notice if they intend to resign, though they have the option of rescinding that notice within three days of submitting it to the employer.
McNeil has said back-to-work legislation is a possibility if there is a strike.
Earlier this month, 420 striking home-care workers were ordered back to work after McNeil's government passed essential service legislation.
The union representing the nurses says talks with Capital Health broke off Monday over the issue of nurse-to-patient ratios, something the union says would improve patient safety.
Capital Health says there is no evidence that shows mandated registered nurse-to-patient ratios guarantee improved patient safety.