Proposal to improve Ashley River flow

Press, 11 July 1979, Page 12

Proposal to improve Ashley River flow

Mr W. Allison, a farm adviser with the Ministry of Agriculture at Rangiora. has devised a method of ensuring satisfactory water flows in the Ashley River for 12 months of the year. Mr Allison, who specialises in agricultural engineering, said that converting the open channel races which serve livestock between the Waimakariri and Ashley rivers to pipes would allow the main race between the two rivers to be re-used. If water was sent down the race from the Waimakariri the Ashley could be used for recreation, gardening, and irrigation by the people of Oxford, Ashley, Loburn, Sefton, Rangiora, and Woodend.

During summer the Ashley often flowed underground in its lower regions, Mr Allison said. At the same time water restrictions applied in Rangiora, fishing was affected, and swimmers and boat-owners had to travel to the Waimakariri or even further, and farm water supplies were affected. The viability of the scheme hinges on a decision by the WaimakaririAshley Water Race Board, which will consider whether the continually rising maintenance costs on its open races would make the change to enclosed pipes a sensible alternative. Mr Allison cites a num-

ber of reasons to support a change. Open races were costly to maintain and wasted water, because only 10 per cent of what entered the races was used, he said. Because they were open the races also became drains. Pollution from dead animals, animal manure, and silt entered the races and eventually discharged back into the Waimakariri River. The possibility also existed of stock diseases being transmitted from

farm to farm down open races.

If stock water was piped little would be required for moving through to the Ashley, Mr Allison said.

He said that the only expense would be fencing one side of the water-race (a fence already exists on one side) and widening a channel as it approached the Ashley. Mr Allison said that he had not determined the cost of establishing the scheme. The cost would have to be balanced against the benefit a continuous water supply in the Ashley would have for people who lived on each side of the river; it would have to be shared by those people.

Mr Allison also said that because the Rangitata and Rakaia Rivers were linked by a channel, and a channel would be built between the Rakaia and the Waimakariri as part of irrigation schemes between those two rivers, a channel between the Waimakariri and Ashley Rivers would give catchment authorities significant control over the flows of all these rivers.