Public complaints alerted the National Rivers Authority (NRA) to the pollution incident on the river Douglas last August. An NRA officer found dead fish downstream of North West Water's Rivington water treatment plant near Horwich.
Inspection of a surface water drain revealed a strong smell of chlorine, and the plant's senior controller admitted that there had been a fault in the chlorination system which had just been corrected.
North West Water staff had to help the NRA officer to take a sample from the drain by climbing into a manhole wearing full breathing apparatus. A formal sample was duly served on the company and proceedings brought under sections 85(3)(a) and 85(6) of the Water Resources Act 1991.
The case was heard by Chorley magistrates on 6 April. The company pleaded guilty to causing water containing chlorine to discharge into the river. It was fined £5,000 and ordered to pay costs of £899.
In mitigation, the company said that the spill had been caused by unforeseen circumstances but rectified once found. However, the plant's controller had admitted to the NRA that chlorine consumption at the plant had increased several days before the NRA called. It took the company three days to trace and correct the leaking pipe which caused the incident.
The case was North West Water's fourth prosecution this year. In January, it was prosecuted for two incidents at Ellesmere Port sewage works which polluted the Mill Brook. It was fined £2,000 for a spillage of polyelectrolyte which staff washed into the stream via surface water drains. The second incident occurred when a sensor failed, allowing foam from an activated sludge tank to be washed into the brook via drains. The fine this time was £4,000.
North West Water was also fined £6,000 in March for a discharge to the Leven estuary from Ulverston sewage works. The works' consent permits it to discharge for 45 minutes commencing half an hour after high water. However, public complaints last September alerted the NRA that discharges were occurring at low tide, and investigations revealed a fault in the works' automatic timing system.
North West Water came tenth in ENDS' latest water polluters league, with 11 prosecutions and fines of £72,000 since privatisation (ENDS Report 230, pp 44-45 ). It had seven prosecutions last year, and on present trends 1994 may be worse still.