Musings about the Manuherikia
Nick Loughnan
AS the extended spell of drought conditions continues to further parch the dry landscapes of Central Otago, it does help bring a sharper focus to the ongoing controversy centred on the flow of water in the Manuherikia River.
The arguments revolve around the health of this vital river and what constitutes an acceptable residual flow in summer when hot dry weeks combined with a lack of any meaningful rainfall see its value for irrigation fully appreciated by those whose livelihoods depend on growing things.
There is a very real, measurable and tangible value to water in these dry periods and it is one which has been recognised the world over since Homo sapiens set themselves apart from other species and began to actively grow food and crops. Water, be it from rainfall or irrigation, is the common vital component and is essential for sustaining our lives.
Living in the Galloway community in the lower reaches of the Manuherikia Valley, and always fascinated by local history, my chance to ‘‘rescue’’ some recollections of older identities came in 2012 when celebrations were held for Galloway Hall to mark 100 years since it opened as the local region’s school.
Conversations with several older local residents, since departed, revealed some salient reminders of how this river has shaped our communities.
And of course, we have altered the shape of its flows in the nine decades since the Falls Dam upstream was built to capture and store its surplus water for future use.
One recollection was of the later part of the gold mining era when Central Otago was the river dredging ‘‘capital’’ of the world. It is an interesting reminder that much of Dunedin’s early architecture and prosperity was derived from the wealth of gold recovered by river dredging activities that would certainly never gain resource consent today.
A late attempt by a dredge in the early 1900s to navigate the Manuherikia upstream as far as Chatto Creek was thwarted when dry summer flows had reduced the river to a trickle. A solution was quickly engineered, with the dredge clawing its way to the recently constructed railway line, where it was dismantled and railed the necessary 8km upstream.
This river has had very low flows, long before the extensive irrigation schemes began. Similarly, the high flows and floods the Falls Dam storage capacity has helped to moderate, have had to be lived with.
The first pupils attending Galloway School from across the other side of the river used a small boat, with an overhead wire cable which the older children had to grasp hand over hand to pull themselves across. On more than one occasion, they were swept downstream in higher flows, but this passage to school was necessary and continued until a bridge was built. Without an education, how else would these children learn to read and write health and safety procedures?
And this first modest wooden bridge was built from rural rates funding, collected from the farms and orchards that were expanding production, made possible only with
Manuherikia’s irrigation water.
That the Manuherikia has been such an integral part of the region’s prosperity for more than a century has become obscured by wider interest groups with different areas of focus.
Some demand that the river retain higher summer flows to preserve both habitat and their right to fish for trout — ironically an introduced species that they hook and then play until exhausted, when the hapless netted creature can be released for another fisher to repeat the performance. Holiday makers frequent favourite swimming spots for a few days over their summer breaks, while the river flows have always been sufficient for this in the lower reaches.
And others lament the depleted river flows for the loss of natural seasonal values which unfortunately reflect the realities of human occupation all over this planet. Our continued survival depends on the modification of river flows to provide us with the ability to harvest and use water for hydro energy and food production.
There is a very real and substantial cost to be borne within the local communities when water from the river is severely restricted.
Manuherikia’s water resource has enabled its communities to meet the significant challenges during periods of extended drought. Without its water, food crops wither and die, orchard irrigation is squeezed, capital breeding livestock have to be trucked out for offfarm grazing or slaughter and serious cash deficits result.
This is the price that will have to be paid for raising the residual flows in the river.
If there is to be an equitable solution to the demands of doubling the residual summer flows in the Manuherikia, then the tangible costs of doing so must also be fairly apportioned.
We need a comprehensive costbenefit analysis to guide us here. But good luck finding other revenue sources to replace the many millions of dollars in lost production.
In the meantime, let us all reflect on the many wider benefits and prosperity that the waters of this precious river have brought to us since permanent human settlement began in this valley.