The current irrigation practices in the Manuherikia and IdaValleys are going to be affected by three principle developments:
- The expiry of mining rights, which is the basis of consenting, in 2021.
- The national requirements for water quality, minimum flows, and the requirement to use water more efficiently
- The need for a significant upgrade to the Falls Dam for safety and compliance.
These impending developments prompted the formation and activities of the Manuherikia Catchment Water Strategy Group (the Group) in July 2011.
The Group commissioned and received three reports critical to developing a whole catchment strategy capable of future proofing our water resources for the whole community. These reports were jointly funded by the ORC and the Community Irrigation Fund (Ministry for Primary Industries (MPI) previously MAF).
In summary the reports conclude:
- The Manuherikia and Ida Valley Catchments are water short; the current water resources are fully allocated.
- 60,000 ha of land is suitable for irrigation, 15,000ha is fully irrigated and 10,000 ha is partially irrigated.
- Increased water storage in the catchment has the best cost effective potential for supporting all community interests.
Community interests in regard to water use being considered by the Group include but are not limited to:
- Current irrigators in agriculture and horticulture and dry land farmers
- Water quality and quantity standards compliance
- Department of Conservation
- Fish and Game
- Town water supplies
- Otago Central Rail Trail Trust
- Local Iwi
- General public recreational water users
- Central Otago Environmental Society
- Businesses in Alexandra and other townships in the catchment
- Rural population decline and vulnerability of rural services
Several options for increasing water availability were identified by two open invitation public meetings in March 2012. A further study has been commissioned by the Group in the form of a
Pre- Feasibility Report investigating these options:
- Raising or renewing Falls Dam incorporating necessary upgrading
- Investigating other potential dam sites in the Upper Manuherikia Catchment
- Investigating other potential dam sites or a larger dam in the Manorburn Catchment
- Improving efficiencies in the existing irrigation schemes
- Gravity pipe supply from Lake Dunstan to Alexandra Flats
The funding for the Pre-Feasibility Report is confirmed and is split between the MPI’s Irrigation Acceleration Fund (50%), ORC (25%) and the catchment irrigation companies and Private Water Right Holders (25%).
The Pre-Feasibility Report is anticipated to be available by the end of 2012 for presentation to the community and stakeholders for consultation and further decisions.