The 16-year-old had collapsed in a street after consuming vodka in the town on a night when temperatures dropped to about -5C.
When found by Mr Green, the teen was unresponsive, hypothermic, and possibly only an hour away from death, police said.
Sergeant Simon Paget said a decision had yet to be made whether a group of 16-year-olds who were also involved would face consequences.
The arrested woman was known to one of the 16-year-olds, and was very upset about what had happened, Mr Paget said.
She will appear in the Alexandra District Court on September 17.
After finding the girl, Mr Green went back and fetched a torch and his wife Wanda Green.
The police were called and then an ambulance.
Her body temperature was down to 34C, Mr Green said.
"She was lucky she was in the recovery position. Had she been lying on her back she could have choked in her own vomit."
Mrs Green said the discovery of the girl was "quite frightening".
"As a parent ... it makes you feel quite afraid that groups of children, or anyone's children, would drink that much and get in to that state and the possibility of what could happen."
People who had been in touch with Mrs Green following the event had said it was "very" fortunate the girl was found.
It was not the sort of thing people expected to happen in Cromwell, she said.
Mr Paget said people, particularly in the 18 to 20 age range, needed to understand the consequences of supplying young people with alcohol.
"We have been proactively policing this for a while now, and we are trying to draw their attention to just how serious the impact can be."
Central Otago District Council deputy mayor Neil Gillespie said he did not think the issue was "huge" in Cromwell, but suspected it did happen.
"But it is clear what has happened should be a huge lesson to everybody that it [supply of alcohol to minors] should not take place.
"We have got to take the positives out of what has happened and learn from that and make sure it does not happen to anybody else."
Southern District Health Board media liaison officer Melissa Garry, when contacted yesterday afternoon, said she would not be able to organise anybody for comment before the end of the day.
Cromwell Youth Worker Trust manager Amy Phillips said she had been instructed by trustees of the group to not conduct any interviews regarding the incident, as it was an issue for police.
