An investigation into the suspicious fire at Levin's Horizons Regional Council depot was stalled for a month due to hazardous substances.
The January fire damaged property, equipment and vehicles stored at the depot.
It was confirmed by police that the depot had been broken into and a quad bike set alight.
Controversial pest control poison 1080 was stored at the depot along with herbicides for weeds, cyanide and rabbit toxins.
Horizons chief executive Michael McCartney confirmed that a 1080 casing was damaged in the fire.