Dam or no-dam scenarios

An overview of the Waimea Plains Water Management provisions in the Tasman Resource Management Plan. The Plan describes what happens if there is - or isn't - a dam.

Introduction

In 2001 the Tasman District endured one of the most notable droughts for decades. This was felt most in the Waimea Plains where the Waimea River ran dry having a significant economic and environmental effect on the area.

In response two actions were taken: the moratorium on all new water permits was confirmed in the light of the significant over-allocation of water while a holding pattern water management regime was instigated and in 2007 put in the Tasman Resource Management Plan (TRMP).

The second action was to set up a community group, the Waimea Water Augmentation Committee, to investigate and identify a means of augmenting the river and groundwater to ensure a secure supply of water for both current and potential water users in the future. This investigation programme has assessed augmentation options and has progressively focussed on the site in the upper Lee River for a major dam.

Tasman Resource Management Plan changes

There have been a series of changes to the TRMP since 2013 for Waimea Plains water management as the proposal to construct the Waimea Community Dam has been developed.

 

2013 and 2015 changes
Two sets of provisions
In 2016 transitional dates changed

Water management without a dam

Under the "no dam" regime, the new minimum flow for the Waimea River will be 800l/sec.

This flow will not protect all the instream values fully and water quality declines at this flow because of higher temperature and algal growth.

Maintaining a flow of 800l/sec will require rationing to begin earlier than previously required.

Five-stage rationing from 2018/19
Water re-allocation
Security of supply

Water Management With a Dam

A new chapter in the TRMP provides objectives and policies for managing significant infrastructure.

At present, this chapter addresses only the proposed dam in the Lee Valley (the dam). The chapter describes the water demand and the shortfall in water supply to meet existing and new water demand. It acknowledges that the dam will cause adverse effects but the water issues are so significant, the adverse effects will be managed through conditions on resource consents.

The dam allows for an improved environmental flow in the Waimea River and the TRMP specifies that if the dam is built, a flow of 1100l/sec is to be maintained in the Waimea River at Appleby.

With the dam, the allocation limits for each of the water management zones where water supply will be augmented, are all significantly increased. They allow for future urban demand and also full irrigation in these zones as well as new irrigation in adjacent zones such as Redwoods Valley and the lower Wai-iti.

Water re-allocation
Security of supply

Irrigation management plans

In either dam or no dam situations, water permit applicants will be required to prepare Irrigation Management Plans.

These will help ensure allocated water is used efficiently and also to help avoid nutrient losses.

Water quality

The TRMP includes new provisions that identify the need for further plan development in respect of managing water quality.

Like the Irrigation Management Plans, this work is required whether the dam proceeds or not.

There are new policies to guide how this work is to proceed and they signal a inclusive approach that involves stakeholders and the community. It also includes new provisions that require nutrient and farm production records to be kept and this information may be used in develop property and catchment scale models.

The Council has since set up the Waimea Water Quality: Freshwater and Land Advisory Group (FLAG) to further this work.

 

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