Up to 30 current and former members of Canada's unelected Senate may be facing charges after a highly-anticipated audit found widespread spending abuses in Canada's upper chamber.

The report from the Auditor General of Canada, released Tuesday, is the culmination of a two-year scandal that has seen a flurry of resignations, a criminal case that touches the heart of the Canadian government in Ottawa, and a growing campaign to abolish Canada's Senate.

The report looked at the spending and expense claims of 116 senators, past and present, in order to determine whether they were abiding by the rules set out in the Senate's spending guidelines.

The audit cost about $21-million to undertake, and uncovered just under $1-million in inappropriate expenses.

Over a two-year period, Auditor General Michael Ferguson dug up senators who were claiming living expenses for homes they weren't really living in, travel costs to send staffers to political events, and thousands of dollars in flights for fishing trips.

The report says that Senator Donald Oliver, who retired in 2013, is responsible for over $48,000 in inappropriate expenses billed to the taxpayer, which includes "a family member's convocation in Kingston, Ontario, at which, according to the senator, he spoke with other attendees about higher education and the role of the Senate", as well as "meetings with family members and a tailor," and, most dubious of all, "a fishing trip."

Senator Marie Charette-Poulin owes, according to the report, over $130,000, mostly for contracts that were riddled with inconsistencies.

Senator Pierre-Hughes Boisvenu, who is still sitting in the chamber, is alleged to have claimed over $38,000 in travel expenses to fly around the country, giving speeches and interviews for organizations he helped found, and selling books he wrote.

Ferguson identifies nine Senators, including those three, who he feels committed criminal fraud. Another 21 senators are alleged to have mishandled public money, and may find themselves inside a courtroom within the year.

Four other senators have already been charged or contacted by Canada's federal police service in regards to their expense claims.

One of those four is Mike Duffy — TV journalist turned star senator for the governing Conservative Party — who was found to be living full-time in the national capital and not, as his expense claims suggested, 800 miles away in Cavendish, Prince Edward Island.

An internal report found that Duffy owed over $90,000 in expenses he had claimed. When informed, the chief of staff to the prime minister surreptitiously cut a check to cover the expenses. After the details of that secret payment were made public, a media firestorm erupted that engulfed the whole Senate and led to the forensic audit of each member of the chamber.

Canada's Senate, whose membership is determined solely by the prime minister, originally served as a check on the power of the elected House of Commons. In order to be appointed, a senator must be at least 30 years old, own $4,000 worth of land, and be a resident in the province for which they are being appointed. A senator can stay in the chamber until they reach 75 years of age.

The chamber studies legislation passed in the lower House of Commons, but generally doesn't change or reject bills.