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Last updated: September 2012
Grantee: Otago Regional Council
Contact Person: John Threlfall
Address: Otago Regional Council, 70 Stafford Street, Private Bay 1954, Dunedin 9054
Telephone: 03 474 7486
CIF funding: $72,500 excl GST
Proposed start date: 1 July 2011
Proposed finish date: 30 November 2012
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The Central Otago Manuherikia catchment is one of the driest in New Zealand and irrigation water is in high demand. The project is a catchment study to assist the community develop irrigation solutions for the benefit of the full valley.
The potential for further growth in the district is related to water availability. This project will provide information that will help the community make water resource decisions, including potential changes in irrigation and storage infrastructure.
The project will collate resource information on the catchments water stocks, the potential future demand for water, and management and distribution options. This will add to and coordinate existing studies and help create a sound foundation for implementing future bulk water storage and distribution options.
This study will answer some key questions, such as:
Six large irrigation schemes have been established in the catchment since 1917, some of which rely on storage from Falls Dam. Water takes from the Manuherikia are dominated by deemed permits, which date back to the gold mining days of the 1800s, and are due to expire in 2021. They were issued by the Warden’s Court under a first-in, first-served priority system. The permitting process did not include any assessment of stream volume, or environmental values.
The combination of a naturally dry catchment; aging infrastructure and changing irrigation methods, and the imminent expiry of deemed permits, poses a significant challenge for water users in the Manuherikia catchment where farmers in the catchment have developed their own methods for carefully managing the water they have available.
Replacement of deemed permits and renewals of resource consents require that water takes will have to maintain surface flows sufficient to maintain ecosystem values, as well as meet expectations of water use efficiency. Detailed water resource data are needed to ensure that future needs are scoped and planned for. This will also assist the transition of deemed permits into the resource consent management regime.
Community input into this assessment is vital to the project’s success. Workshops and smaller focus groups are planned to enable the community and stakeholders to discuss the views, concerns, and desires they hold for the catchment. Following assessment of the community values linked to water (economic, environmental, cultural/iwi, and recreational), options for the management of the resource for the catchment as a whole, will be brought back to the community for further consultation.
The key steps to be taken, starting June/July 2011 are:
This project has been completed ahead of schedule with the following objectives met:
After consultation with the Manuherikia Catchment Water Strategy Group, five options to be carried over to the pre-feasibility study were chosen. These were:
The project has now passed into the next phase looking into more detailed pre-feasibility options and is receiving financial assistance through the Irrigation Acceleration Fund.
The Manuherikia Catchment Water Strategy Group (MCWSG) has been formed, whose main objective is to facilitate optimum use of water in the catchment to realize the full potential for growth in the area.
Three stages within the overall CIF project were identified by the MCWSG:
The three stages were put out to tender and Aqualinc were appointed the groups consultant.
The definition of the potential irrigation demand has been completed and a discussion report was circulated to the Group pre-Christmas. Comments and feedback were incorporated into the final report which was given to the MCWSG in mid February.
The initial assessment of the water availability for meeting the agreed demand is underway reviewing previous reports and collating hydrological data. MCWSG will be providing essential input to this stage.
Overall the project is progressing well ahead of schedule and final reporting of all three stages is expected before the end of May 2012.
The MCWSG has set up a sub-group to deal with communication. This was seen as a crucial step to ensure the whole valley is kept fully informed of progress and feedback from all stakeholders is considered.
The Group has also been progressing follow up projects, including a detailed options study and has submitted an Irrigation Acceleration Fund application.
In July and August a series of meeting were held by Central Otago District Council (CODC) and the Otago Regional Council with key stakeholders and Agribusiness representatives in the Manuherikia Valley. A decision was made to form the Manuherikia Catchment Water Strategy Group (MCWSG), comprising an independent Chair, representatives from every irrigation company; private right holders; Falls Dam company; CODC; and the ORC.
The Group's main objective is to facilitate optimum use of water in the catchment to realise the full potential for growth in the area.
A request for professional services was issued and Aqualinc has been engaged to carry out the initial land and water stages of the project.
The ORC has been progressing technical work which will assist the assessment of water availability and different storage options. A naturalised synthetic flow record has been developed for the Manuherikia, based on the temporary flow sites installed above all abstraction points. From this, naturalised flows have been modelled for the available long-term record. This naturalised flow record allows the modelling of different storage options, allocation regimes and environmental flows to determine the water available for abstraction and the resultant impact on river flows.
An assessment of soil moisture deficit has also been made, which can supplement irrigable area maps to get potential irrigation demand.