A report commissioned by Canterbury Regional Council says all the area's groundwater is linked. It says irrigation demands therefore have an effect on the region's entire supply.
Groups applying for water recently suggested that each aquifer is independent, and taking water from one would not affect the levels of the entire central Canterbury supply.
Regional council chairman Sir Kerry Burke says the new report refutes this claim. He says central government intervention is needed and the regional council will raise the issue with various government ministers later this month.