Gemma Duncan is making the film as part of her master of arts degree in screen production at Auckland University.
During her undergraduate degree, at Unitec, she took large digital photos of historic sites around the South Island and spent two and a-half weeks in Cromwell.
"I just fell in love with the place. It's got a rich and in-depth history."
For the latest project, Miss Duncan hoped to interview individuals and representatives of community groups about what it was like to live in Cromwell before the dam was built and what it is like now.
She has already been in contact with the Cromwell i-SITE and the Cromwell and Districts Promotion Group.
She is aware that construction of the dam was controversial.0
"The last thing I want from the documentary is to make a statement about whether or not the dam should have been built. It's more about focusing on what was there and what still is.
"If physical history is lost, people still have their memories. It is about loss but it's also about community spirit." The length of the film was yet to be determined, she said.
"It all depends on what I find. It's very early in the game right now, so, although I have a vision, it's hard to say how long, as the nature of documentaries means everything changes as you meet the people along the way."
Historic footage might be included, but the focus would be on people's memories and what Cromwell was like to live in today.
Miss Duncan is working to secure funding for the film but hopes to be in Cromwell within the next month for pre-production work, before returning in August for filming.
She plans to have the film finished by the end of the year.
"Then I've got to look at getting it screened. I'm hoping a film festival might pick it up. I'd also like to think we could have some sort of community event in Cromwell, to show the residents."
