"It was the highest reading in my 10 years as a police officer," Croucher said.
The woman instantly lost her license for 28 days and will appear in the Christchurch District Court next month.
Croucher said she is likely to face further penalties from the court.
The woman admitted to police that she is an alcoholic and officers offered her support in dealing with it, which she declined.
It is an extremely disappointing situation for police, Croucher said.
"We have seen an increase in high alcohol readings in Selwyn over the last month or so.
"We are increasing our presence so be prepared to be stopped by police."
Croucher said he will be requesting an order through the courts for her to attend and complete an intensive stop-alcohol programme upon conviction.
• If you or someone you know needs support and treatment to reduce their alcohol intake, call the Alcohol Drug Helpline on 0800 787 797, visit their website, or free txt 8681 for confidential advice.