Ontario's spending watchdog has uncovered a spike in sick pay to school board employees, and revealed that hundreds of government-owned buildings are sitting empty, wasting millions every year.

Those are among the findings in Auditor General Bonnie Lysyk's annual report to the Legislature, released Wednesday, with election day in Ontario just six months away.

The auditor's report also found that the provincial agency that pays private electricity generators to feed power to the grid is spending millions of dollars more than necessary. Those costs get passed on the hydro customers on their bills.

Lysyk's audit of four school boards found that the amount of sick days being taken by employees has jumped 29 per cent since 2011-12, after the province stopped allowing teachers to bank their unused sick time and cash it out as a bonus upon retirement. She also found that the amount of sick pay spent by the boards she surveyed has jumped 32 per cent in the same time frame.

The auditor found that 812 provincially owned buildings are vacant, and maintaining them is costing Ontario taxpayers $19 million a year. The finding means about one in six provincial government buildings is sitting empty.

Lysyk says the properties could be put to better use. She criticizes Infrastructure Ontario, which manages the government's real estate, for being too slow at selling off the buildings or transferring them to municipalities or non-proft groups.

Other key auditor findings include:

More than half of all biopsies, and urgent surgeries for nearly all types of cancer, are not being performed within the 14-day targets set by the Health Ministry.

There are more households on the waiting list for social housing (about 185,000) than there are social housing units in the province (167,000). Each year, only five per cent of people on the waitlists get a spot.

The government spent $58 million on advertising last year, more than it has in a decade, and nearly one-third of that spending was for ads designed "to make the government look good," the auditor said.

The auditor disclosed more details about how privately-owned power generation companies have been "gaming the system," as revealed first by CBC News on Tuesday, taking advantage of lax oversight to bill the electricity system more than they were entitled to.

Lysyk criticized the province's Independent Electricity System Operator (IESO) for failing to act on recommendations that could have saved Ontarians millions on their hydro bills. The Ontario Energy Board had warned the IESO repeatedly that its programs for compensating private power plants were flawed and vulnerable to abuse.

The IESO's own audits found that nine power plants claimed $260 million in ineligible expenses, but the agency only recovered $168 million, Lysyk revealed.

The auditor is raising concerns that the IESO's working group that is redesigning the electricity market system is not representing the interests of hydro customers and instead includes people who work for power companies under investigation for overbilling.

Ontario unprepared for emergency response

Ontario is not prepared to respond to disasters and emergencies, the auditor says. The province's emergency response plans have not been updated in eight years and the cabinet committee that is supposed to oversee emergency management hasn't met since 2009.

The auditor revealed that 80 per cent of all emergency practice tests conducted by provincial ministries in the past five years happened in meeting rooms or on paper, and did not involve actual simulations that required personnel and equipment to move anywhere.

Homeowners who appeal their property assessments are stuck in a huge and growing backlog, even though the number of appeals filed has been dropping significantly in the past decade. The auditor found that 16,600 outstanding appeals are yet to be heard by the Assessment Review Board. It is common for property owners to wait four years for decisions, the auditor found, delaying potential refunds of property taxes.

"The province needs to move quickly to resolve these backlogs," Lysyk said. "Behind every appeal in the backlog is a property owner who needs clarity."

The Ontario Municipal Board also comes in for criticism. The auditor found three municipalities that spent up to $4 million each on external legal fees and expert witnesses to defend their official plans at the OMB, even though these plans had already been approved by councils and the province.

Half of the farmers who received money from the province's $100 million a year fund to compensate for crop damage and unexpected price drops did not actually have lower income than they did the year before receiving the compensation.