"It is kind of spawning a new industry. A lot of principals now say they have been inundated with offers by private companies.
"The ministry's advice is that at this stage it's not necessary, but I think some principals and boards are erring on the side of caution and spending considerable amounts of money."
Mr Walsh has criticised the law as it applies to schools, saying principals feared they could face fines of up to $600,000 or up to five years' jail if students or staff are hurt.
Workplace Relations and Safety Minister Michael Woodhouse has repeatedly said such fears are unfounded.
The new law would not prevent outdoor school activities or camps, he said.
Mr Walsh accepted the risk of prosecution was small, but said the penalties existed and would have a chilling effect.
Some schools had raised the possibility of removing adventure playgrounds, he said, and he knew some schools were reviewing camp arrangements with regard to adventure activities.
They feared not only liability but also the cost of having the accredited staff to supervise activities such as kayaking and abseiling.
Grant Lander, headmaster of Hamilton's St Paul Collegiate, which runs a six-month programme for Year 10 boys that involves many adventure and outdoor activities, said his school had decided not to alter its activities, despite significant concern about the new laws.
Other schools were unlikely to make a call on camps until later in the year, he said.
"I know of schools that are really worried and are probably looking at changing certainly some of the opportunities they have for those kids."
Iain Taylor, president of the Principals' Federation, a union representing more than 2300 principals, said that despite assurances, the new legislation was "intimidating".
He hoped schools wouldn't opt for less adventurous camps, "but I'm sure there will be schools who do that".
The ministry has set up a website with information on the health and safety changes, established a working group with principal, union and board representatives, and held more than 40 workshops.
Its advice includes that the laws should not curtail out-of-school activities, given that schools should already have effective health and safety programmes in place.
The ministry also repeats Mr Woodhouse's assertion that maximum fines are imposed in "extreme circumstances for the most serious offences where the duty holder had been reckless".
Katrina Casey, its deputy secretary of sector enablement and support, said the health and safety advisory group will next month discuss the implications of the new law, including on camps and extracurricular activities.
Mr Walsh, who is part of the group, plans to ask officials to put in place monitoring so that if the health and safety reform does result in changes to camps, playgrounds or other activities it would be flagged.
Schools come under the act
The Health and Safety at Work Act comes into effect on April 4, and outlines the responsibilities of staff including those defined as officers - a person who has significant influence over the management of a workplace.
In a school environment, officers will include principals and board of trustees members.
Paid officers such as principals may be subject to prosecution and fines or jail if they fail to meet the duty of due diligence.
The Government says maximum fines are imposed only in extreme situations, and schools complying now under the existing law have nothing to fear.
The Secondary Principals' Association has questioned why existing penalties should be increased and why industries such as mining were not targeted.
