Sir, - Dr G. W. Smillie (July 21st) feels there is a bias in the emphasis being attached to the use of phosphate fertiliser and its effects in water pollution.
There have been many discharges of slurry and silage effluent into our smaller water supplies in recent years. It is probable that there is an amount of such discharges into other waters not used for drinking waters. Many of our rivers show evidence of enrichment but are flushed by periodic heavy rain falls. Our lakes are not so easily cleaned.
Perhaps Dr Smillie could comment on the likely effect of largescale application of phosphate in upland areas where the soil is not very deep and the rainfall is above average. The Flesk Valley in Co Kerry is a good example.
Extensive afforestation has resulted in such spreading of phosphate. It has been reported that some spreading in upland areas is done by helicopter. Would it be reasonable to assume some leaching into the numerous streams in the area, all of which drain into Lough Leane, Killarney? Is it just a coincidence that this lake "greened" in 1997 and only the unusually wet summer has saved it this year, though there is a plentiful algal growth in the lake at present. The lack of sunshine seems to have prevented a repeat.
Would Dr Smillie expect the same dynamics to apply in the deep, fertile soils of Munster and Leinster and such upland areas?
We anglers have increasingly witnessed pollution of our waters during the last 20 years far away from any urban or industrial areas. Agricultural experts tell us that many farmers are spreading excess phosphates. It can hardly be to the farmers' benefit. Our fragile water-based environment is most certainly not receiving any benefit. - Yours, etc., John Behan,
Frankfield, Douglas, Cork.