Mr Walsh told the Herald that principals were concerned about liability -- they can be fined up to $600,000 if accidents occur -- and increased compliance costs.
Some principals were paying consultants thousands of dollars for their health and safety systems to be reviewed, and others had sought legal advice.
Mr Walsh said that schools were considering whether activities like camps would need to be altered, but most were still in a "wait and see" mode.
"I can tell you there are some things already happening. Pakuranga College has decided to buy a scissor lift, because under the new act you can't use a ladder as a workstation. Above a metre now you require scaffolding or a harness, so the old days where a caretaker could clean out leaves from a gutter is either not allowed or it is a very expensive exercise.
"So larger schools are buying a scissors lift. It is very, very expensive. But I think they have worked out that, overall, with the act if they have to use harnesses and scaffolding to change lightbulbs and clean leaves out of gutters and do other things, then that's a better investment ... but a lot of schools are not in a position to do that."
Workplace Relations and Safety Minister Michael Woodhouse said the school that had banned tree climbing had overreacted.
"It is a complete nonsense. There is nothing in the new law which would prevent anybody from doing the normal activities that kids have been doing in playgrounds forever."
The Health and Safety at Work Act 2015 comes into effect on April 4.
Under the new act, those with significant management influence over a workplace -- including principals -- may be subject to prosecution and a fine of up to $600,000 and five years in jail if they fail to meet the duty of due diligence.
That has spooked some principals, Mr Walsh said. He believed it was inevitable that a school leader would be prosecuted, and that would be the test case.
However, a WorkSafe NZ spokesman said talk of banning kids from climbing trees, going on camps or making farm visits was a "massive overreaction".
"While schools are workplaces as well, they are very much at the lower end of the risk scale ... the new law doesn't create new risk areas to be managed -- it clarifies who has what duty.
"Climbing a tree has some risk, but that doesn't mean a kid now can't climb a tree. Reasonably practicable steps to manage that risk might include ensuing kids don't climb a tree overhanging a road with traffic, or going up trees with diseased or broken branches."
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.
