asked the Secretary of State for Northern Ireland what has been the effect of the discharge of the Caugh Hill treatment works on the ecology of the Cashcapel Water, the Owenreagh River and the River Roe since the present plant began to operate; and how the ecology of the Owenreagh River in the stretch affected by the discharge of the old waterworks, but not by the new, has changed since the new waterworks began operations.
pursuant to his reply [Official Report, 13th November 1978; Vol. 958, c. 121–22], gave the following answer:Information on the ecological conditions of these rivers comes from sampling invertebrates and juvenile salmonid populations in the Owenreagh River by the Foyle Fisheries Commission. An exercise undertaken by the commission in 1976 indicated significant increases in these populations since earlier sampling in the period 1968 to 1971.In addition, since 1973 the Department of the Environment for Northern Ireland has undertaken regular sampling and chemical analysis of the Owenreagh River some 11 miles downstream from the Caugh Hill treatment works and results have shown the river to be unpolluted. Regular monitoring of the River Roe has indicated that it also is unpolluted. The effects of the discharge from the Caugh Hill works appear to be negligible. Moreover there is no knowledge of any changes in the ecology of that stretch of the Owenreagh River receiving discharge from the old waterworks but not from the new works.
asked the Secretary of State for Northern Ireland what is the chemical composition of the discharge from the Caugh Hill waterworks; and what is the chemical composition of the Cashcapel Water above the discharge point in drought conditions and below the same point in the same conditions when the discharge is occurring.
pursuant to his reply [Official Report, 13th November 1978; Vol. 958, c. 122], gave the following information:The discharge from Caugh Hill water treatment works into the Cashcapel River consists of hydrated aluminium oxide with absorbed natural colour and solids from the Glenedra River and the Altnaheglish reservoir. The aluminium content of the discharge, which is intermittent, is 100 mg per litre with a maximum suspended solid content of 2,112 mg per litre.Tests carried out during the 1975 drought on the Cashcapel River indicated that the suspended solid content in the natural water when there was no discharge from the works was 75 mg per litre and 650 mg per litre during discharge.