Author:G Crowcroft, R Bannister, D Henihan
Source:Auckland Regional Council
The Auckland Regional Council reviews water resource monitoring data and resource consent data on an annual basis. The Auckland region’s principal planning document, Proposed Auckland Regional Plan: Air, Land and Water (PARP: ALW) (2001), identifies 13 high use aquifer management areas and 8 high use management stream areas. These areas are under pressure from demands of water abstraction and need careful management to ensure their values are maintained or enhanced. ARC collects rainfall, stream and groundwater monitoring data in most of these areas. This data is reviewed to ensure these high use management areas are not being adversely affected by water abstraction.
The hydrological year ending May 2005 was 20% drier than average. This had the effect of reducing stream flows and groundwater recharge. Drier than average conditions also resulted in higher than average water demand in some parts of the region, particularly demand for municipal supply and irrigation.
Stream flows in three High Use management area streams ran below mean annual low flows during the 2004/2005 year. This was due to the effects of the lower than average rainfall, especially in late summer and autumn and the increased demand for water abstraction. Enforcement action has been taken against consent holders in these high use management areas that exceeded their consent allocations; thereby exacerbating the low stream flows.
Most High Use aquifers have groundwater availability limits set in the PARP: ALW (2001). These figures are the maximum amount of water that can be allocated to users, to ensure that the aquifer is not over pumped. Groundwater levels are monitored in the aquifers to ensure water levels are not dropping in the long term. Currently Omaha, Waiwera and Parakai high use aquifers are fully allocated. Groundwater allocation to consent holders remains within groundwater availabilities. Groundwater levels at Waiwera Geothermal aquifer fell below the management target. Applications for consent are currently being processed and allocations reviewed. Groundwater levels in Volcanic and Waitemata Aquifer management areas came close to site minima in autumn 2005 as a result of increased water abstraction and/or reduced rainfall at this time.
The greatest demand for water in the Auckland Region is for Municipal supply. Water Care Services Ltd have consent from ARC to take surface water from dams in the Waitakere and Hunua Ranges and groundwater from the Onehunga aquifer for bulk water supply. They also have consent from Environment Waikato to water from the Waikato River to meet Auckland’s water demand. Excluding municipal supplies, industry, then irrigation are the next greatest water users by volume
Auckland Regional Council technical publication TP300