"We spent time trying to understand the effect that this would have on flora and fauna and had some robust discussions with GWRC.
"The Friends are concerned that the most serious potential direct effect is on invertebrate life in the streams and that may affect native fish."
Mr Bell said surveys carried out by the Ministry of Environment-funded Kapiti Biodiversity Group over the past two years had shown a serious decline in macro-invertebrate life in the farm streams.
"Although these two surveys cannot prove that stream life has been degraded by the previous spraying, they certainly show it's a possibility.
"Before any spraying commences, we would like the council to determine what surveys and tests would help determine whether it affects the biological health of these streams."
However, so far they have rejected that request, he said.
Mr Bell said the park was a recreation reserve on Department of Conservation-owned public land.
"The legislation that governs this land says that it should be used for recreation and that flora and fauna must be preserved.
"That is why we cannot understand council's unwillingness to do all they can to show that their commercial use of the park is not harming our waterways and the native insects and fish that live in them.
"We should be getting to a position where the streams and forests are abundant with life for the enjoyment of locals and visitors."
Greater Wellington Regional Council parks manager Amanda Cox said, "We realise people really love and value this park and so do we.
"The area being sprayed is relatively small, 19.2 hectares of plantain/ clover with a red clover/tall fescue pasture, and an additional 4.05 hectares in kale, compared to the total park's 650 hectare area.
"The goal is to make the pasture more resistant to weeds in the long-term so eventually no spray will be needed.
"Farming is a really important means of land management at this stage for Queen Elizabeth Park.
"If no spraying was done, farming would be impractical, the weeds would get out of control and ultimately hinder public access and enjoyment.
"The contractors take every precaution when spraying the weeds - from using the least toxic but most effective spray through to targeted boom spraying on a tractor in fine weather and no wind.
"The waterways are all fenced off; this work will not affect fish and other stream life."
She said spraying would take place in spring.
"There are no dates set as it is weather dependent."
The spray areas were east of the farm race out to State Highway 1 and to the south of recently replaced culverts.
"It is well away from areas accessible to the public."
She said chlorpyrifos wouldn't be used as part of the chemical application.
"The herbicides are targeted for the specific weeds that are growing in the area."
The quantities to be used are: Weedmaster TS470, 139.49 litres, Headstart, 15.36 litres, Kamba 500, 2.43 litres, Prestige, 1.42 litres, Sequence, 2.03 litres, Sharpen, 480 grams, Thistrol Plus 38.4 litres.
The insecticides will be: Ampligo 405 millilitres, Sparta 465 millilitres.
She said the spray work was set out in the regional council's parks management plan.
"The GWRC land management and biosecurity departments have reviewed the proposal and made the comment 'all seems consistent with a well thought out pasture renovation programme'.
"All the work will be carried out by suitably qualified contractors, consistent with regulations and guidelines eg fine weather, no or minimal wind and avoiding sensitive areas such as waterways."
