KEY POINTS:
Edmund Hillary Outdoor Pursuits Centre is being prosecuted over the deaths of six school pupils and a teacher on the Mangatepopo River.
Question were raised over why the centre did not heed heavy rain warnings before the river deaths on April 15.
Six students and teacher Anthony McClean were canyoning on the river near Turangi with instructor Jodie Sullivan when they were swept to their deaths.
"The department considers that there were steps the outdoor pursuits centre should have taken to better ensure the safety of the group on the day," said the department's central region manager of health and safety services, Mike Munnelly.
Four charges were laid yesterday under the Health and Safety in Employment Act 1992.
One charge relates to the centre's obligation to ensure the safety of other people in the place of work.
Another relates to its obligation to ensure that its employees' actions didn't expose others to avoidable risks.
And two relate to obligations to protect the centre instructor who went into the gorge with the school party.
The principal of the school involved in the tragedy says the school still supports the centre.
Murray Burton, of the Elim Christian school in Pakuranga, said the school acknowledged the impact the decision would be having on centre staff, and parties from the school would return to the centre when the case was over.
Mr Burton said the department's investigation also found the school had met its obligations under the act and would not be charged.
Centre chairman Rupert Wilson said the centre was reviewing the tragedy and "welcomed any expert scrutiny and suggestions for improvement.
"Losing seven lives is a tragedy beyond belief, and the Department of Labour is doing what it thinks is right."
He said the prosecution would be a test case in "determining the parameters ... for the outdoor education, in providing an exciting and meaningful experience, but still achieving the safest possible environment."
The gorge where the accident happened had not been used since the tragedy and would continue to be off limits, Mr Wilson said.
The charges were laid in the Wellington District Court, but will be filed in the Taumarunui District Court - the closest to the outdoor pursuits centre's head office and the scene of the incident.
The first hearing is likely to be in four to six weeks.
If the centre is found guilty of the charges, it can be fined up to $250,000 for each offence. It can also be ordered to pay reparations to victims' families.