Waimea Groundwater Quality Survey

Sampling has been completed and the report is now available to download and read.

Between October and December 2021, a water quality survey was undertaken in the Waimea Plains. This is the sixth and most recent water quality survey undertaken in the plains.

Read the full Technical Report Waimea Groundwater Quality Survey 2021 (pdf 11 MB).

Of the 137 bores/wells sampled in the Waimea Plains, 56 sites (41%) had nitrate-N below 50% of the MAV (below 5.6 g/m3-N), 42 sites (31%) were between 50% of the MAV and the MAV (between 5.6 and 11.3 g/m3-N), and 39 sites (28%) were above the MAV (above 11.3 g/m3-N).

The highest nitrate-N concentrations in 2021 were found at the intersection of Bartlett Road/Ranzau Road West (31 g/m3-N) and along Blackbyre Road (30 g/m3-N). All bores/wells sampled between these two locations exceeded the MAV for nitrate-N. The area between Bartlett Road and State Highway 60 is where the UCA and the AGUA merges together and becomes hydraulically indistinguishable. Any discharge of nitrate-N from the UCA would be noticed here and would be contributing to the elevated nitrate-N concentrations at the Bartlett Road/Ranzau Road West intersection. Blackbyre Road is outside of the UCA reach, however water from Bartlett Road is likely to travel towards Blackbyre Road as the flow of groundwater progresses towards the coast.

Unconfined groundwater south of Brightwater shows most sites sampled being well below 50% of the MAV. North of Brightwater on both sides of the Waimea River, nitrate-N was near or above 50% of the MAV.  East of the Waimea River and east of Burkes Bank, the majority of all four aquifers were near or above the MAV. West of the Waimea River, bores/wells in the AGUA along Cotterell Road/Moutere Highway/River Road/Waimea West Road were also near or above 50% of the MAV. It was anticipated that these areas would have higher concentrations of nitrate-N due to the overlying horticultural and agricultural activities.

The large number of samples where nitrate-N concentrations are near/above 50% of the MAV across the main horticultural and agricultural areas on the Plains shows that input from present-day activities are contributing to nitrate-N entering in the groundwater in all four aquifers.

You can learn more about nitrates in the Waimea Plains here.

More information

If you have any questions about the survey itself, please email [email protected]. Alternatively contact Joseph Thomas, Resource Scientist, on 03 543 8494.

If it is a health-related question, please contact the Nelson Marlborough Public Health Service on 03 546 1537 or via email at [email protected]

The Nelson – Marlborough Public Health website has more information on Drinking-water supply safety, including specific advice on how to ensure your bore or well is secure, as well as information on water supply treatment options.

If you have any questions about your drinking water bore or supply, you can contact Tasman District Council Environmental Health Officers on 03 543 8400.

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