Severe weather forecast for the end of this week suggested plenty of rain for most parts of the region, while also alleviating the need for implementing broader water restrictions.

Tasman Dry Weather Task Force has recommended that current Stage 2 restrictions (a 35% cut to authorised weekly usage) be maintained for the Motupiko water management zone, beginning Monday 31 March.

Water users in the Rainy zone remain on a cease take under their own specific consent conditions.

Waimea Community Dam-unaffiliated permit holders moved into cease take on Monday 23 March and will remain so until a 7-day moving mean flow at Wairoa at Irvines exceeds 6000 litres per second (l/s). As of Wednesday 25 March, the flow was 1990 l/s.

No other water management zones are affected by these restrictions – this includes Council-managed reticulated water supplies which are subject to alternative and different restriction criteria.

However, without the advent of rain in the coming days, additional restrictions would have been brought in across the district.

The driest areas continue to be the Motupiko, Wai-iti and Waimea areas.

The Motueka River and associated catchment are well above trigger levels - the Motueka river at Woodstock was flowing at 9090 l/s - above the WCO trigger of 7000 l/s.

However, Golden Bay rivers were showing reduced levels, with the Aorere dropping to between a 1:5 and 1:10 year low flow.

Soil moisture levels are also low both in the Waimea and Golden Bay. But more dew is setting as we move further into autumn.

Our dams continue to supplement key water supplies in several areas.

The Waimea Community Dam is 96.7% full and currently releasing at 800 l/s.

The Wai-iti dam is 83% full and we have been releasing water from the dam for over two weeks.

Both these dams have the capacity to maintain flows at the lower reaches for this irrigation season if required.

The Cobb dam, near Upper Tākaka, is about 46 % full this week as it generates power off and on, while also helping maintain flow at Te Waikoropupū Springs (~9530 l/s today).

The DWTF has reiterated the positive impact of the Waimea Community Dam in avoiding major restrictions this season.

Under a no dam scenario – as was the case prior to the 2024-25 season - all water permits would have been between a Stage 3 and Stage 4 rationing trigger (a 50 – 70 % cut from old authorised rates) or cease take in many cases.

At the same time, urban supply users in Richmond (including those in Nelson supplied via the Richmond water supply), Hope, Brightwater, and Māpua/Ruby Bay households and businesses would have been limited to Phase E restrictions, allowing only for minimum health needs and prohibiting water use for car washing or watering plants.

Staff will continue to monitor river flows, groundwater, and soil moisture levels in the coming days.

This week’s decision will be reviewed by the Dry Weather Task Force on Tuesday 31 March to ascertain the need for continued or further measures.

You can keep up to date with groundwater and river flow data by visiting our environmental data portal www.tasman.govt.nz/my-region/environment/environmental-data-portal .

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