"We have not increased our donations so the figure seems a bit off but we have made a real push to attract international students who bring significant revenue for the school and lower the financial impact on our domestic families."
Mr Walsh said the vast majority of families were happy to pay school donations.
"When there is a small number of families who can't pay the fees or donations, we don't insist on it and have an allowance in our budget to accommodate them but most parents understand their donations go towards providing the best opportunities and environment for their children to learn in.
"We do our very best to minimise costs for parents, but the reality is there is a gap between the actual cost of running a school and the funding allocated to education by the Government," he said.
"The funding that is provided by the Government does not cover what parents expect schools to cover so as a school, we need to find ways to fund 'extras' such as new electronic devices and equipment, co-curricular activities such as music and the bus we run for students.
"The Government has a choice to make. Either fund the full operational costs of a school or allow schools to charge fees. If the Government insists it wants free education in New Zealand, it has to be funded," Mr Walsh said.
Ministry of Education figures show nationwide donations and fundraising went up $1.2 million from 2013 to 2014, reaching $161.6 million. That's $8.4 million more for New Zealand schools than in 2010.
Ngakuru principal and Rotorua Principals Association president Grant Henderson said if the Government wanted Kiwi kids to have access to free education, donations needed to be taken out of the equation to reveal the true shortfall.
"If you look at most school finances, it doesn't appear schools are struggling to stay open on the face of it.
"However, if you minus the donations and additional grants schools apply for, the true gap is clear. In 2014 we had a big fundraising effort for the upgrade to our school pool which is where the $22,000 increase in donations came from.
"This year we will be feeling the brunt of our decile increase and will be fundraising to keep our power on. This is an example of why we need to look at school finances without the top-up from donations."
He said while $2.6 million worth of donations looked like a large sum, if broken down into cost per pupil, the sum was not as alarming.
"I think that figure speaks volumes about what kind of community we as schools are operating in. Parents recognise the importance of their children getting a world-class education and are willing to help achieve that."
Labour's education spokesman Chris Hipkins this week branded "free" education a joke. He said when schools could not deliver the basics without donations it was time to sit up and take note.
But Education Minister Hekia Parata said parents contributed just $1.80 for every $100 spent by the taxpayer on education.
She said it was important the system allowed parents who were able and wanted to, to provide extra.
At the same time the country's poorest schools were still getting more from decile-related funding than high-decile schools pocketed from donations and fundraising.
Additional reporting by NZ Herald