Fish were partially dissolved yesterday after strong acid leaked from a chemical plant into a small stream.
More than 19 tons of hydrochloric acid leaked from a 25ft (8m) tall tank at a chemicals blending firm's premises in Hailsham, East Sussex, overnight. Most of it was contained within a protective wall which surrounds the chemical tanks, but about 500 litres (110 gallons) escaped - Chemaide's managing director, John Bell, estimated - and some drained into the Knockhatch stream which passes through the industrial estate.
Some of the acid evaporated, forming a vapour cloud above the premises. Police advised people living near by to stay indoors and keep their doors and windows shut.
About 70 firemen attended through the night wearing breathing apparatus to protect them from the corrosive fumes. They pumped water on to the surrounding ground to dilute the acid. The Government's National Rivers Authority created a dam made of lime-filled sacks across the 6ft wide stream in an effort to neutralise the acid. Upstream of the dam, however, the water was acidic enough to kill and dissolve life.
The authority appeared to have succeeded in preventing any significant pollution reaching the Cuckmere, a trout stream which the Knockhatch joins half a mile away.
''The lime dam will have to stay in place for a couple of days until the acid is neutralised and the pH of the water drops to more normal levels,'' said a spokesman. ''As long as we don't have a downpour of rain overnight, which would cause the dam to be breached, the situation now looks to be contained."
Mr Bell would not comment on what caused the leakage, but said the Government's Health and Safety Executive was investigating. ''The spillage appears to be much less severe than was first feared,'' he said.
Most of the spilt acid was pumped into a tanker lorry and driven away for disposal.