Part of the stormwater system in the Alpha Series subdivision, in Wanaka, has been found to be not working properly as the two organisations have been claiming.
The two groups are concerned stormwater and sediment from the new subdivision could enter Bullock Creek, smothering aquatic life and heightening the flood risk.
Bullock Creek flows from the subdivision through Fish & Game's property and dozens of other properties, on its way to Lake Wanaka.
Partly because of the groups' concerns, the Queenstown Lakes District Council arranged for Beca Consulting to carry out a design and performance review of the stormwater system.
3 Waters contract manager Simon Mason said in a statement the system used "trident arches'' which were intended to allow most of the water to soak into the ground.
"Beca concluded that the stated design soakage rates are not being achieved in reality, and the actual performance is significantly lower than anticipated by the system's designers.''
Mr Mason said the council was working with developer Allan Dippie, of Orchard Road Holdings, to find a solution, and Fish & Game would be involved.
Fish & Game chief executive Ian Hadland said he was grateful for the review but not satisfied "on a number of fronts'', and he called for the Beca report to be made public.
"Friends of Bullock Creek and Fish & Game have been very patient through this process but given the deficiencies have now been identified, action needs to be taken urgently.
"The performance of the onsite stormwater system is heavily dependent on local soakage which has now been found to be abysmal.''
Mr Hadland said the area had a high watertable and poor drainage "exacerbated by conversion of the land from farmland to hard surfaces such as roads and rooftops''.
He was unhappy at a suggestion Fish & Game's land might be "considered as part of a solution''.
"The Fish & Game Council has been very clear with the developer and the QLDC that this is their problem to solve.''
Mr Dippie said both the QLDC and his company acknowledged there were "extra challenges'' in providing stormwater solutions "since the council moved subdivision engineering requirements to what is called a low impact design philosophy''.
"Previous to this, most subdivisions simply piped stormwater to either a creek or a lake.
"Low impact design involves more sustainable and environmentally-based solutions and Alpha Ridge is an example of this philosophy.''
Mr Dippie said soakage was not as great as engineers had calculated, and "in-ground storage and disposal'' was being designed for future stages.
"Once completed this subdivision will provide a good example of low impact design and sustainable stormwater management.''
A copy of the report has been requested from the QLDC.
