Groundwater is water that exists beneath the earth's surface, in underground streams and aquifers. The quantity and quality of groundwater in Northland largely depends on the type of rock (geology) within which it is contained (called an aquifer system). In Northland, the main aquifer systems are contained in basalt rock, like Whangarei and Kaikohe, or in the Aupouri sands. Rainfall is the main recharge source for these aquifers. Recharge refers to the amount of water that drains through the land and into groundwater.

The Council monitors groundwater in Northland in three main ways:

· State of the Environment (SoE) monitoring to record the general state of groundwater quality and quantity, and change over time

· Monitoring of activities that may affect groundwater to prevent or minimise any adverse effects caused by these activities

· Investigating individual aquifers where specific problems have been identified

Groundwater Monitoring in Northland 2008-09

· 84 bores were monitored for groundwater levels

· 7 groundwater quality sites were monitored as part of the National Groundwater Monitoring Programme

· 32 groundwater quality sites were monitored as part of the Regional Groundwater Quality SoE Programme

· 16 sites were monitored as specific groundwater investigations

· 127 new bores (wells) were inspected for compliance and bore construction requirements

· 216 resource consents for groundwater use were monitored for compliance with consent conditions

· 3 specific groundwater investigations were done on aquifers - Ruawai, Russell and Taipa

· 2 additional investigations started in Whatitiri and Maungakaramea

· 8 sites were age tested to determine the average age of the groundwater in certain aquifers in the region