Miriam van Dingenen, agency manager and clinical team leader, said in those 30 years the only changes made to its original charter document was adopting an "H" in the spelling of Whanganui and using the word "survivor" rather than "victim".
Ms van Dingenen said many Wanganui people did not understand the effects of this sort of abuse.
"We're dealing with males and females, children and adults. And generally 90 per cent of the sexual offending is done by people who are known to the person being offended against," she said.
She said statistically one in four women up to the age of 16 are likely to be offended against and very conservatively one in 10 men.
"Break that down into our population [in Wanganui] of 43,000 and you can do the math. Through the course of a lifetime we're talking about thousand of people being affected," Ms van Dingenen said.
She said importantly was the fact more people had become less tolerant to this type of offending so more was being heard about it.
Along with Ms van Dingenen, the centre has three other front-line staff including an arts therapist, a clinical psychologist and a psychotherapist. There is also a programme facilitator, who also works as a family support worker, and an administration person.
She said it was not always easy for a person to open up about the effects of sexual abuse.
But she said everyone in the agency held tremendous respect for that person's courage to have survived their experience and the steps they were taking to heal that trauma.