Manawatu-Wanganui Regional Council says TAG Oil was fully compliant during all construction and drilling activities at its Ngapaeruru-1 well site near Dannevirke.
Council officers made 11 site visits to the exploratory well and ground water and surface water sampling showed no incidents recorded.
TAG Oil chief operating officer Drew Cadenhead said the company set very high standards for staff and contractors and this will be the same for all operations carried out on the East Coast.
Operations at the Dannevirke site have now finished and TAG Oil is analysing the data to see if the well is commercially viable.
Mr Cadenhead said the data reviewed to date is encouraging, but no final decisions have been made on whether to commence commercial drilling.