AquifersNgā puna manawa whenua

Our Hawke’s Bay aquifers provide groundwater that we use for drinking, agriculture, horticulture, industry and the environment.

There are a number of productive aquifer systems in Hawke’s Bay, two large – Heretaunga, Ruataniwha – and smaller ones from Mahia to Waipukurau.

Here is a useful infographic about our Aquifers.

What we know about aquifer water quality

Water quality in our main Hawke’s Bay aquifers is generally very good and meets NZ Drinking Water Standards. 

Hawke's Bay Regional Council operates more than 100 wells for monitoring short and long term changes in groundwater levels and quality.  We monitor key water quality indicators such as nitrate-nitrogen, bacteria levels (Escherichia coli or E. coli), dissolved iron, dissolved manganese, and total hardness.

Some of the smaller northern aquifers have naturally occurring higher levels of iron, manganese and total hardness. This is because the water picks up minerals as it moves through the rocks and aquifer.

Shallow aquifers (<20m depth) are likely to receive contamination due to overlying land uses. Localised elevated nitrate and/or E. coli levels can occur. Therefore, anyone using shallow aquifers to provide drinking water are recommended to regularly get water tested or treat water to ensure it is safe.

The longest monitoring record is near Fernhill where groundwater levels have been measured since 1968.  Most monitored wells were established in the early 1990s in response to requirements under the Resource Management Act (1991).

We also gather water use data from irrigators and industry, which is valuable information to help everyone make the best water management decisions.

What we know about the Heretaunga Aquifer

Some of the earliest scientific information for the Heretaunga Plains comes from drilling records at Meeanee, where an artesian bore flowed with a positive pressure of six meters above the land surface in 1867, which is about the same height measured today.

In the 1990’s, the Regional Council and GNS Science (previously IGNS) embarked on a five-year research project to improve our understanding of the Heretaunga aquifer. This investigation examined drill logs, deep drilling studies and geophysical, chemical and hydrological data.  This work was used to help develop our current policies for groundwater management in the Hawke’s Bay Regional Resource Management Plan (RRMP).

The Regional Council is currently working with stakeholders to review land and fresh water management policies for the wider Heretaunga Plains, including the aquifer and the Tūtaekurī, Ahuriri, Ngaruroro and Karamū  – referred to as the TANK catchments.

The Regional Council  in collaboration with other organisations, has developed computer models for the Heretaunga aquifer and its rivers and streams. These models help us and the community better understand and decide how water is used in the TANK catchments.

Heretaunga – quick facts

• Size:    460 square kilometres 

• Depth:  The full depth of the aquifer system has not been explored.  Most groundwater is taken from depths shallower than 50 metres. The deepest well is a monitor well drilled 220 metres and used for monitoring.  

• Consented volume: The total groundwater allocation is approximately 160 million cubic metres per year.  

• Number of consents: Approximately 1,700 resource consents are issued to take this water.

• Management Plan: Proposed changes to the Regional Resource Management Plan for the Tūtaekurī, Ahuriri, Ngaruroro and Karamū (TANK) catchments and Heretaunga Aquifer are currently in progress.

What we know about the Ruataniwha Aquifer

The Regional Council has developed a computer model of the Ruataniwha aquifer system. This was used to develop land and water management policy and rules for the Tukituki Catchment through the Regional Resource Management Plan Change 6. Limits for water allocation and water quality were set so that this resource can be used sustainably.

Ruataniwha – quick facts

• Size:  Approx 800 square kilometres.

• Depth:  The gravels which make up most of the aquifers within the Ruataniwha aquifer system are thought to be up to 200 m deep in places. Most groundwater is taken between 30 and 120 metres.

• Consented volume:  Total groundwater allocation is currently set at 28.5 million cubic metres per year.

• Number of Consents: Approximately 60.

• Management Plan: Regional Resource Management Plan Change 6 in 2015 set limits for water quality and quantity.

Smaller aquifers

Mahia, Nuhaka, Wairoa, Esk, Poukawa, Papanui, Waipukurau/Waipawa. 

These smaller aquifers have lower use – mostly domestic and stock water supply, with some irrigation.  Northern aquifers have naturally occurring higher mineral content (calcium, magnesium, iron, manganese) and some sites exceed the NZ Drinking Water Standards.