Chairman of the Henley Lake Trust, Dr Tenick Denison, stands on the charred remains of an observation hide.
Vandals have set fire to and destroyed an observation hide at Henley Lake.
The arsonists used an accelerant to set alight the hut at the southern end of the park.
"It's sad that this sort of rubbish takes place. You have to question the mentality of people who do this kind of thing," says Dr Dennison.
"It makes you spit tacks. We had just painted the hide about a month ago," he says.
The building was purpose built to observe wildlife while remaining hidden from view.
The hide, which was built in 1988, survived an attempt to burn it down eight years ago, but on this occasion was completely destroyed by the fire.
A man walking his dog early in the morning alerted police to the fire at 7am on Wednesday.
Trees surrounding the burnt out hide were also damaged in the arson, and police found a jug smelling of some kind of accelerant nearby the site.
"What bothers me is that they also burnt some of the trees that were planted 14 years ago and they take a long time to grow to maturity."
Dr Dennison says the hide will be rebuilt, though the location may be changed to a spot where observers can see along the length of the two ponds.
Last year ten trees were burnt down over the New Year period.
"We hope this kind of thing doesn't happen again this year. We have taken steps in the planting, so there is no grass around the trees to catch fire."
The Henley Lake Trust has just finished improvements to the park's pathways and has installed 10 wooden benches at various places along the walk.
"I hope we don't have idiots around to damage those as well," says Dr Dennison.
Local residents sponsor all the new benches.
Henley Lake is home to 45 species of Wairarapa birds and also has special weed eating Asian carp to deal with the weed growth in the lake.
"We need more carp per hectare to get on top of the weed problem. We also have a weed cutter, but that is restricted to cutting the weed to a metre below the surface, and the weed grows back up when it is cut," says Dr Dennison.