To rub salt in their wounds, families living in some parts of Kew, Hawthorn and Toorak will still be included in the state school's enrolment boundary.

The changes were made in response to a new $43 million co-ed Richmond High School, which will open its doors to year 7 students next year.

The intake zone for the popular girls school will dramatically shrink in 2020, excluding most residences west of Burnley Street. It will still include Richmond homes east of Burnley Street and many families will be zoned to both schools. 

Victorian Greens leader Greg Barber said he had been contacted by residents who were "shocked" by the changes.

"A public girls only high school is a pretty unique thing," he said.

"Many parents in the area had no idea that a new Richmond High meant they would lose access to Melbourne Girls College."

Richmond is a marginal seat and its local MP, Planning Minister Richard Wynne, is keen to promote the new Richmond High in the lead up to the 2018 state election. He promised the new school ahead of the last election.

One parent, who did not want to be named, said his school choice had been taken away due to the zone changes. He had been planning to send his daughter to MGC, and had remained in Richmond so that she could attend the school. When his daughter starts year 7, she will be excluded from the school's zone.

"It is equally distressing to know that girls living much further afield in suburbs such as Hawthorn and Kew retain access to the school whilst Richmond locals who have planned their lives based on this educational option have been excluded," he said.

Justin Naylor, a father of four who tirelessly campaigned for the new Richmond High School, and was celebrating the start of its construction earlier this week, said existing zones should remain.

"Richmond residents should have choice," he said. "Now is not a time to create this restlessness."

A spokeswoman for Education Minister James Merlino said students were entitled to go to their designated neighbourhood school and could choose to attend another school when there was room.
  
"This strikes the right balance between ensuring families can choose for their child to attend another school and not allowing other children to lose out on attending their local school as a result of that choice," she said.

Yarra councillor Stephen Jolly raised concerns about girls living in public housing in north Richmond being excluded from a single-sex education.

An informal arrangement has previously meant that the school must provide girls who live south of Victoria Street with automatic entry to the girls school if they want to attend. It is unclear whether this would continue.

MGC's enrolment policy gives priority access to girls living just outside its zone once all local students are accommodated.

The designated neighbourhood school is the school that is nearest to the student's permanent residence.