Caution On Pollution

Press, Volume CIX, Issue 32050, 26 July 1969, Page 2

Caution On Pollution

Once New Zealand’s lakes were polluted with the blue-gfeen algae now contaminating Lake Forsyth the disastrous effects would be almost irreversible, Dr Elizabeth Flint, a Christchurch biologist said at a meeting of the Federation of University Women in Christchurch recently. The algae, which flourished on effluent from sewage, food processing, tanneries, and other industrial plant, gathered on the lake surface in a thick scum. It made swimming and boating unpleasant, and its “awful stench” rendered surrounding land valueless for settlement. Scientists did not have a remedy other than using eopper to kill the algae but the long-term effects of the lake after this treatment were not known. “We have examples of this all over the world and yet people wanted to put effluent in Lake Brunner,” Mid Dr Flint She was referring to the Grey County Council’s application to discharge effluent from Its sewerage oxidation ponds at Moana into Lake Brunner. The application was turned down by the Westland Catchment Board last June. Protest Last year a group, of Moana ratepayers protested against the proposed discharge of effluent into the lake and proposed that it be piped into the Arnold River. The group said it was prepared to pay higher rates to meet the expense. The council’s consulting engineers are now preparing revised plans for the siting of the ponds and discharge into the river. Dr Flint considered this a "very wise decision” and explained that swiftly Ji owing rivers were less affected and quicker to recover from effluent discharge than lakes. “New Zealanders must be informed of the risks involved in polluting lakes so they will be ready to accept

the more expensive method of diverting effluent through other channels," she Mid. Effluents containing a high degree of nitrates and phosphates encouraged the growth of certain plants, particularly the blue-green algae, which required a very nutritive solution. This was the same principle as feeding the soil to get * good crop. The problem was causing great concern in America where a lake even deeper than Manapouri bad been affected. One of the causes of pollution tn New Zealand—misplaced aerial top-dressing—-was very hard to control. Laws governing discharge of mining, industrial and sewer age effluents might control this aspect Soil Erosion Soil erosion, which also enriehed lakes, could be prevented by afforestation such as was being done in the North Island. “The more you feed the lake the bigger crop of algae you get and unfortunately it is always the plants you don’t want” said Dr flint Dr Flint's talk was one of three addresses from federation members who discussed their work. Dr Peggy Liddell spoke of her work in the Christchurch Public Hospital radio therapy department and Mrs Gillian Finnegan explained the tasks of a computer programme analyist in the computer centre at Ham.