Saskatchewan's Brad Wall is still Canada's most popular premier, but his approval rating has slipped to its lowest level ever, an Angus Reid Institute poll says.

According to the firm's latest survey, 57 per cent of Saskatchewan residents approve of the job Wall is doing.

That's nine points lower than the rating he received in the spring.

It's also the lowest rating Wall has ever received.

However, it's still the highest rating of all premiers — an achievement Wall has maintained for many years.

At the other end of the scale, Kathleen Wynne of Ontario has the lowest approval rating of all premiers after years of steady declines: 20 per cent.

Premier Brad Wall's approval ratings have been above 60 per cent for much of the last five years. (Angus Reid Institute)

The Angus Reid Institute says the drop in popularity comes after a particularly rough patch for Wall, including ex-deputy premier Don McMorris pleading guilty to a drinking-and-driving offence and controversy over the potential sale of Crown-owned SaskTel.

Also happening this summer was the violent death of an Indigenous man, Colten Boushie, on a rural property, which ignited a debate about racism in Saskatchewan.

The Husky oil spill, which had some people questioning Wall's ongoing support for pipelines, was also in the headlines throughout the summer.

The results were based on an online survey of 4,629 Canadian adults in what the company says was a randomized and representative sample of Angus Reid Forum panelists from Sept. 5-11.

A randomized sample of this size carries a margin of error of plus or minus 2 per cent, 19 times out of 20.