Ashley River plan threatens irrigators

Press, 24 April 1986, Page 23

Ashley River plan threatens irrigators

By

HUGH STRINGLEMAN

Up to 60 irrigators on the banks of the Ashley River could be seriously affected by proposed water allocations contained in a North Canterbury Catchment Board draft management plan for the river. In recent days the realisation that they could face reduced water reliability has dawned on many of these existing water users and the potential threat to their economic viability has angered many. The “retrospective” nature of the draft management plan has particularly annoyed those affected. The exhaustive, costly and ultimately inconclusive Rakaia River Study revolved around arguments about potential large-scale water abstractions. The Ashley plan could restrict the allocations of existing water users, although their, current water rights would give them assured supplies until those rights expired. The North Canterbury Catchment Board pub-

lished the “Ashley River Catchment Draft Management Plan” in March and invited public submissions to be lodged before April 30. Recently Mr Bill Allison, of the Rangiora M.A.F., has urged local irrigators to submit their own objections. He is writing the M.A.F.’s own submission and has called a meeting to put catchment board staff before water users who are affected. Board staff have assured objectors to the water allocations in the plan that it is a draft, open to amendment, and that all reasonable public submissions will be carefully considered. But the Ashley management plan is breaking new ground for the board’s staff and directors, not to mention the people of the North Canterbury and, as with many of its deliberations, reservoirs of wisdom will be required. The plan defines a restricted area, consisting of the river bed and those of its tributaries and a long, narrow terrace of “recent

gravels” on the south bank, extending only a few hundred metres from the banks and from the Mount Thomas Road in the west to near the junction of Tulls Road and State Highway One (south of the highway bridge) in the east.

The board’s investigative staff decided that the groundwater in these “recent gravels" could not be meaningfully separated from the subterranean flows in the river bed.

So the management plan permits “abstractions from the Ashley River upstream of Kings Avenue (Waikuku) and from its tributaries above State highway one, and from groundwater in recent gravels adjacent, provided that the end use is shown to be beneficial.” “Maintenance flows, that is flows at which abstraction ceases, and allocation rules are as follows: • December to March Inclusive: maintenance

flow 3 cumecs at Ashley Gorge. Flow from 3 to 4 cumecs (cubic metres per second) entirely available for abstraction. Above 4 cumecs, flow to be shared one for one (in-stream with out-of-stream uses). • April to November inclusive: maintenance flow 4 cumecs at Ashley Gorge. Flow from 4 to 5 cumecs entirely available for abstraction. Above 5 cumecs flow to be shared one for one.” Users of water from the lower tributaries of the Ashley, including the Waikuku, Taranaki, Lower Ashley and Saltwater Creeks, are prevented from drawing for irrigation when the flow in these streams drops below pre-determined levels for each one. Groundwater users outside of the restricted area are bound only by the terms of their rights and the management plan proposes nothing new for them. Inside the restricted area, and/or drawing water directly from the river system, are about 60 farmers and horticulturists. They include some private spray irrigators on the north bank, about the Garry and Okuku tributaries, who developed into irrigated cereal growing and stock finishing in the

last few years, usually at considerable expense on borrowed money. More than 25 orchardist members of the Loburn Community Irrigation Scheme also draw their supplies for trickle irrigation of fruit trees from the Okuku River. This very successful scheme has revitalised the Lobum district, enabling the replanting of newer, export varieties of pip and stonefruit. About 200 ha of Loburn orchards, plus another 40ha potential Lobum irrigation development and a further 85ha of orchard development elsewhere on the banks of the Ashley are directly threatened by potential water restrictions. Irrigation is now accepted as essential for export fruit growing to reach the quality required. Without irrigation the Lobum orchards were, and would be again restricted largely to local, oversupplied markets. “The Lobum trickle irrigation scheme ensures minimum quantity with maximum use,” said the president of the local Fruitgrowers Association, Mr John Lakeman. “The amount of water we abstract doesn’t matter to the total flow of the Ashley system,” he said. In fact the water right for the Lobum scheme, held by the Hurunui County Council, amounts to a flow of only 0.05

cumecs, about one-sixtieth to one-hundredth of the various maintenance flows proposed. Other Ashley irrigators have rights between 20 and 80 litres per second, or 0.02 to 0.08 cumecs, except for two large border-dyke irrigators nearer Waikuku who have rights over 226 litres per second each. The total rights granted over the Ashley, Makerikeri, Okiiku and Garry water amount to just over one cumec, out of a “total known maximum summer abstraction of 1.58 cumecs.” The estimated effective peak demand has been calculated at 0.85 cumecs out of the main river system and 0.4 cumecs out of groundwater. Many rights holders are reportedly not drawing water at all. But the potential threat to the score of small users who are drawing water from the Ashley system, and who have based their economic livelihoods on this water availability, arises in the historical records of the river’s flow. The fine “balancing act” of the catchment board considers the claims to water of irrigators, wildlife, fish, recreational users and others. The maintenance flows, or minimum flows, of 3 and 4 cumecs have been proposed to satisfy these claims. For instance the

plan says that a flow of 3 to 4 cumecs at the gorge would give one cumec at Lowes Corner and that this would be “appropriate” for recreational and fisheries protection. However often the Ashley has in the past fallen below 4 cumecs (at the gorge) before December and below 3 cumecs between December and March. It has been calculated that the cropping irrigators would face severe restrictions on their water before Christmas when a shortage would cause most agronomic and economic effect, in two years out of 10. Loburn and Rangiora orchardists could predictably face irrigation scheme shutdowns after Christmas during fruit filling in four years out of 10. Both arable farmers' and horticulturists have said that one season’s shutdown would be enough to put them out of business. “The restrictions proposed in the management plan could wipe me out financially,” said one farmer. “The Ashley has always gone dry and nothing we take out of the system will help that,” said Mr Lakeman. , The plan does seem to take a sledgehammer to crack a nut, the nut being a comparatively small ac-

tual irrigation abstracttion, which has such economic importance to the small number of users. The plan itself says: “The most significant impact will be on farmers already irrigating from the combined ground-water-Ashley River system. “They will have greater restrictions .on water availability than existed under the previous water allocation provisions. “For example, in some summers there will be periods of several weeks or more when no water will be available for irrigation. “During periods of limited water availability, rostering of abstractions will reduce the effective peak demand and allow the available water to be more evenly allocated between users. But no such voluntary allocation roster has yet been established within North Canterbury. In any event, because it is believed that the actual irrigators draw such a comparatively small amount even of the small total rights, the allocation of low flows may not prove a problem. It is the prospect of being denied water completely, at river flows below 3 and 4 cumecs atdifferent periods of the year, which has angered local residents.