Wairarapa water scheme options narrowed further

A plan to increase the supply and reliability of water in Wairarapa has moved a step closer following work over the past five months to further narrow options for water storage and distribution schemes.

The Wairarapa Water Use Project is investigating the viability of a multi-purpose water scheme that would collect and store water then distribute it for a variety of economic and community uses during the dry season in an environmentally sustainable way.

It has the potential to increase irrigation in the Wairarapa valley from 12,000 hectares currently to about 42,000 hectares. Other uses could include increasing low summer river flows, recreation, stock water, frost fighting, hydro-electricity generation and urban water supply.

The latest investigations further assessed 14 possible water sites identified in March this year against technical, financial, environmental, social and cultural criteria, and their ability to supply areas of potential demand.

Of the 14 sites, mostly on privately-owned land, five have now been selected as priorities for more detailed investigation. They are in the White Rock, Mangatarere, Black Creek, Te Mara and Tividale areas. Three other sites are being kept in reserve at Kiriwhakapapa, Te Ore Ore and Martinborough South.

Six sites have been discounted from further study – Mauriceville West, Dorsets Road and four in the upper Tauweru area.

The project’s Leadership Group this week endorsed the site selection and next phase of investigative work. Leadership Group chair Fran Wilde said good progress had been made in what was a complex investigation that took a long-term view of how water could be supplied throughout the Wairarapa valley.

“The project is still at a conceptual stage and we don’t yet know how many schemes might be viable – there may be one or a combination of several. The aim is to investigate this thoroughly up-front so good decisions can be made about any future development that, if viable, would need to be staged over time.

“There is much more work to be done, starting immediately. We are acutely aware that the on-going investigations create uncertainty for owners of property in the areas of interest and we aim to reduce that as quickly as possible.”

The next stage of work will include more detailed assessments of demand for water, potential scheme income, environmental, social and cultural impacts, geological and geotechnical aspects, available water resources, potential funding models and planning implications.

Expected to be complete by the end of 2014, the next stage of investigation will determine any schemes that are worth taking forward to a full feasibility study in 2015. Any storage sites found to be unsuitable as work progressed would be removed from the list at the time.

The project investigations will run alongside separate work on a new regional plan that will see the soon-to-be-formed Ruamāhanga catchment committee decide priorities for land and water management across the Wairarapa valley. The community advisory group called a ‘Whaitua Committee’ would be the first of five to be established in the greater Wellington region.

“On-going conversations with all parts of the community through the catchment committee, the project’s stakeholder advisory group and wider activities are vital in developing a viable and environmentally sustainable project,” Fran Wilde said.

Community drop-in days in each of the five priority site areas in October would allow members of the public to meet with project staff, ask questions, give feedback and receive more information.

Project investigations are being jointly funded by the Greater Wellington Regional Council and the Ministry for Primary Industries’ Irrigation Acceleration Fund.

All project reports and further information are available at www.wairarapawater.org.nz

Background information – 13 September 2013
The project is investigating a multi-purpose water scheme for Wairarapa to collect and store water then distribute it for a variety of economic and community uses. This will be done in a way that promotes sustainable management of land and water and creates regional prosperity.

The scheme(s) would harvest, store and distribute water in the Wairarapa valley.

The Tararua mountain range west of Wairarapa captures an annual rainfall of 5-6 metres. However, comparatively little of it falls on the good soils of the flat valley floor, much of which are potentially suitable for high-value production.

In a community-based approach, project governance is in place with a 14-member Leadership Group representing the Wairarapa community and greater Wellington region.

A Stakeholder Advisory Group enables community views, expectations and project information to be developed and shared. Independently chaired, the group has 19 member organisations representing iwi, environmental, farming, health, recreational, local government and business interests.

Project investigations are being jointly funded by the Greater Wellington Regional Council and the Irrigation Acceleration Fund (IAF) which is administered by the Ministry for Primary Industries.

One or more storage reservoirs may be developed to provide water to different parts of the valley. The eventual number and location of these will depend on a wide range of factors including:
• suitability of dam sites (geological and geotechnical aspects)
• demand for water
• water availability
• environmental, social and cultural effects
• overall financial viability of each scheme
• availability of land

Potential water storage sites and distribution systems are in the early stages of investigation. A combination of water storage sites and distribution networks may be the best solution for providing an increased and reliable water supply for Wairarapa. A staged approach to this is likely to be needed.

Currently about 12,000 hectares of Wairarapa land are irrigated. It is estimated that new water harvesting and storage could increase this area to about 42,000 hectares depending on demand.

An initial on-farm study of potential demand has so far found a strong demand for irrigation water although information is not yet available on how much it would cost to supply that water.

A wide-ranging and robust analysis of the potential environmental effects is being made. Issues to address include:
• catchment hydrology – rainfall, river flows, surface and groundwater and their interaction
• ability of existing river flows to be harvested, when and how
• effects on existing river systems and in-stream habitat soil suitability
• land use change and intensification
• farm management practices using irrigation
• interaction with tangata whenua & cultural values

Costing of potential schemes is extremely preliminary due to the large number of assumptions and uncertainties at this early stage of the project.

Further information from www.wairarapawater.org.nz

ENDS

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