A 1080 poison drop in Auckland's Hunua Ranges remains on hold after the Environment Court extended a temporary injunction today.

Friends of Sherwood Trust has gone to the court to halt the 1080 drop by helicopter into the Hunua Ranges, which supplies 65 per cent of the city's water.

The council had already begun covering the bush with non-toxic pre-drop pellets, to be followed up with 1080 within 7-10 days, when a temporary injunction was granted earlier this week.

A council spokeswoman said today the court reserved its decision until next Friday or earlier if Judge Melanie Harland is able to deliver a decision.

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"Any decisions about delivering our programme will be dependent on the court's decision and the weather forecast – we need the right wind conditions and a fine weather window on either side of the bait application," the spokeswoman said.

The aerial drop was publicly notified at the end of August to reduce pest numbers in the Hunua Ranges.

Despite safety measures enacted by Auckland Regional Public Health Service, the trust had applied for orders preventing the deposit of any 1080 poison baits in the bed of any river in the Hunua Water Catchment. The trust was also concerned about the potential the impact of 1080 on the flora, fauna and water supply.