De Jong was remembered at the university as "a bright, cheerful, kind and diligent member of the student community".
AUT Vice Chancellor Derek McCormack told the Herald De Jong was well respected by both her lecturers and peers.
"We are saddened to learn that one of our students passed away tragically over the long weekend. Our thoughts are with Rachael's family and friends at this extremely difficult and sad time. AUT extends our sincere condolences."
Despite it being university holidays, he said any students who needed support could contact AUT's counselling services on 0800 288 864.
De Jong's family live in Torbay and she had worked at Pukeko Bakery on Auckland's North Shore.
Her boss at Pukeko Bakery, Jason Olmstead, paid tribute to De Jong.
"The saddest thing of all, the thing that makes me so angry inside, is that she was just getting started," Olmstead said.
"She was so young and had so much more to offer. I can't imagine the person she was going to become, the people she was going to touch, the extraordinary deeds yet to be done."
Olmstead said there were "no logical explanations" and "no imaginable reasons" why De Jong would be taken from her loved ones.
"I get it. People die, but what possible divine plan or karmic reason could there be to deprive the world, all the people who loved her, of even one more small moment with her? It does not make sense."
Olmstead said he later began thinking perhaps De Jong had already fulfilled her purpose in everyone's lives and had "already given us her gifts".
"Now it is up to us to embrace those qualities that made her so special, made us feel so special while she was here.
"Whether we accept it or not it is now our turn pay it forward, to try to live our lives as best we can, as she lived hers. We must honour her memory with good deeds, service and kindness to others."
He and the others at the Pukeko Bakery would "cherish her memory and the gifts she has given us forever".
De Jong's friends have also taken to social media to pay tribute to her.
One young woman wrote she was "honestly lost for words" when she heard of De Jong's passing.
"The most beautiful girl inside and out I have ever met, just gone like that. You were a part of our family for many years Rachael De Jong and you will be utterly missed.
"I love you so much and I'm just so happy that you touched so many people's hearts in your 21 years of life. Rest easy angel, the Currans are gonna miss your pearly white gorgeous smile, and laughter."
Another Facebook user said: "[You] always had a smile on your face and a laugh to match".
"I have been so stuck for words because the shock is so so real, you are an angel now looking down on us all, in our hearts forever ... I wished it weren't true, we all did fly high, will miss you always."
A spokeswoman for Mercury Energy, which operates the dam, said the company was conducting a safety review and an internal Employee Assistance Programme was available to staff.
"The initiative is available to all staff including the Taupo team who may be more impacted than the rest of the team."
Police said De Jong's death had been referred to the Coroner.
Worksafe said it was investigating and was unable to provide any further information now the investigation is under way.
