Lake Ellesmere 'on danger’

Press, 24 May 1977, Page 6

Lake Ellesmere ' on danger’

“Disastrous consequences” for Lake Ellesmere have been suggested as a possible result of continued discharge of sewage into the lake. The Ellesmere County Council wants a water right to discharge effluent from the Lincoln sewage treatment plant into the L2 River—something it is already doing, and has been doing since 1968. The situation was described at yesterday’s special, tribunal hearing of the regional water board as “an illegal discharge, for which a water right should have been sought many years ago,’’ by Mr P. C. Mac Nab, counsel for the objector, the North Canterbury Acclimatisation Society. : An objection was also j lodged by the Tai Tapu and Districts branch of Federated Farmers, but a letter tread to the tribunal said that the farmers’ objection had now been met since the recent changed operation of the plant was producing a better I quality effluent.

The chairman of the tribunal was Dr W. R. Holmes, and the members were Dr F. Wilson and Mr J. D. Annan. The Ellesmere County Courtcil was represented by Mr A. Hearn and evidence was given by the County Engineer (Mr G. L. Tapper), Mr D. L. Steven, a consulting engineer, and Dr I. D. Blair, a microbiologist (for the acclimatisation society). A technical report was presented by Mr R. B. Ayrey, an investigating' officer with the North Canterbury Catchment Board, i Mr tapper told the tribunal That the council had "inherited” the plant from the Ministry of Works, which had built it in 1959 to treat effluent from Lincoln College. Since then it had been enlarged to take sewage from the township, the D.S.I.R. land the Wool Research Organisation. The council began to run the plant in 1968, and in 1973 made application for a right to discharge which was deferred by the board. In 1975 the Catchment Board and the

regional water board said the application could go ahead. The acclimatisation society’s objection was that the effluent, enriched with nitrates and phosphates, found its way into Lake Ellesmere, a water resource of national and local importance. The lake was therefore in danger of becoming eutrophic and the council should, if a right was granted, be compelled to remove the phosphate—the dangerous element—before discharging. The hearing was taken up with technical data about these chemicals and their effects, and the possibility of their removal by the addition of other chemicals, but all the experts agreed that the major problem was a lack of real knowledge about Lake Elies- 1 mere. Mr Ayrey quoted from a Town and Country Planning Appeal Board hearing in 1970, in which a discharge right was sought on another matter, and the board said: “The further nutrient eni richment of the lake may lead

to conditions having farreaching and disastrous consequences, but it cannot be said at the present time just when these conditions are likely to occur.” Mr Ayrey said levels of these chemicals were similar in other watercourses which emptied into the lake, but it was not possible to pinpoint their origins. For that reason the acclimatisation society wanted control of the effluent from the sewage works, said Mr MacNab. It was the one area that could be dealt with. Dr Holmes asked Dr Blair whether he had any idea of the phosphate generation from die fish and fowl at the lake. Dr Blair: “Your guess is as good as mine, although it must be a lot. I couldn’t speculate on it compared to, say, a growing population like Lincoln.” Dr Holmes: “We shouldn’t come to the idea that fish and Towl are pure, and man is not.”