Welcome to the MCWSG October newsletter: to keep you informed of developments for future water use in our catchment.
A meeting will be held at the Omakau Rugby Club rooms Thursday 8th November at 3 pm to present a range of options that have been identified for the Manuherikia Catchment and a preliminary assessment of the costs associated with each option.
To assist irrigators with identifying land use opportunities five Case Studies based on existing operations in our community will also be presented.
In this newsletter we would like to restate the background and clarify the base line costs of a “do minimum” option.
Why do we need to make changes?
Water use legislation in New Zealand is based on the premise that:
“clean fresh water is becoming a scarce resource and therefore the use of water requires careful management”
This premise has resulted in the following new legislation to maintain the careful use of water:
- The Resource Management Act(RMA)
- The NPS for freshwater Management
- The Measurement & Reporting of Water Take; Regulations 2010
Background to current water use:
There are six farmer co-operative irrigation companies operating in the Manuherikia Catchment. The irrigation schemes are based on open race infrastructure, some of which was installed for gold mining and dates back to the 1860s. The purpose built irrigation infrastructure was constructed in the period from 1912 to 1936. In addition to the schemes there are a number of private water permits.
Currently, about 25,000 ha of the catchment is irrigated. Of this 25,000 ha, only about 15,000 ha is fully irrigated. The remaining 10,000 ha is only occasionally irrigated with unreliable water, in some cases as little as 2-3 times per year. Since the last of the irrigation schemes were installed in the 1930’s, there has been little investment in water infrastructure.
What are the implications of the new legislation?
Most of the schemes and private water takes are authorised by mining privileges that collectively expire on 1 October 2021. New water permits will be required. National and Regional policy under the RMA now requires higher standards to be adhered to with respect to freshwater management.
These standards include minimum flows and residual flows in watercourses, allocation limits, greater accountability for the quantity of water taken, water quality limits and limits on discharges back into the environment and consideration of the proximity of the take to the use location.
What is the “do minimum” option?
The “do minimum” option is based on the changes (and costs) that irrigators will have to meet in order to comply.
In addition to upgrading systems on-farm, irrigators will need to fund irrigation scheme upgrades. A major cost is remedial work to Falls Dam, and an increased storage component has been factored into the “do minimum.”
The logic for this is to ensure investment in on-farm irrigation systems is supported by reliability of supply to the existing irrigated area.
The Upper Manuherikia Valley Distribution Report suggests to achieve this the dam needs to be raised 5 m, costing about $12M.
This cost would need to be funded by Omakau main race irrigators, Blackstone, Manuherikia and Galloway Irrigation Schemes.
In return these irrigators would receive high supply reliability.
Irrigation scheme off-farm distribution systems also need to be upgraded. All water intakes will require measurement and many will require provision for fish exclusion or fish passage.
Automation and buffer storage ponds will be required to deliver the on-demand flow necessary for spray irrigation. Lining of leaky races will be necessary to comply with current efficiency requirements.
An estimation of the off-farm costs of the “do minimum” Falls Dam upgrade and the distribution upgrades are expected to be in the region of $1000 to $2500 per ha.
Please note the range of these figures is Aqualinc’s initial suggestions only as the apportionment of these costs have yet to be discussed.
How does the ‘do minimum” cost compare to other new development options?
Preliminary development costs for the alternative options identified for significant new water storage and distribution systems allowing an increase in irrigable area in the Upper and Lower Manuherikia Valley will be presented at the meeting to be held Omakau Rugby Club rooms Thursday November 8th at 3 pm.