Tammy Louise MacKay was charged with possession of drugs with intent to sell or supply and selling a prohibited drug after an undercover police sting earlier this year.

MacKay sold 13.8 grams of methyl amphetamine to an undercover police officer at the Burlington Hotel on January 23.

Prosecuting lawyer David Lima said the purity of the drugs were well above street level.

The court was told McKay has been a regular intravenous methyl amphetamine user for the past three years.

Previously McKay was a successful swimmer and competed in international swimming competitions in the butterfly and until 2003 had regularly participated in the Rottnest Channel Swim.

MacKay has four children all under the age of five. Three of the children live with MacKay’s former partner while she had full custody of her youngest, who is 12 months old.

MacKay’s defence lawyer Max Owens said his client was determined to do something better in her life.

In handing down her sentence District Court Judge Mary Ann Yeats said MacKay came before the court in a terrible situation.

“I can see you are heavily addicted to methyl amphetamine and it is a tragedy,” Judge Yeats said.

“A person that heavily involved in drug use is a risk in the community.”

Judge Yeats said MacKay’s case was a serious example of commercial low end dealing and MacKay had to be punished for what she had done.

“I am of the view (a term of) imprisonment has to be imposed,” Judge Yeats said.

“Your crimes are too serious to suspend them at this time.”

Judge Yeats said MacKay’s former experience as an elite swimmer was an indication of the determination she would need to turn her life around.

“To have been able to achieve what you have done in sport is no easy thing ... there is your potential for life,” Judge Yeats said.

Judge Yeats urged MacKay to seek drug substance abuse counselling during her imprisonment.

MacKay will be eligible for parole after 18 months.