An airport faces a hefty fine for killing more than 5,000 fish by polluting a river with runway detergent.
Chemicals were accidentally hosed from a runway into a stream
Magistrates at Haywards Heath heard how chemicals used to clear rubber, oil and grease from a runway at Gatwick Airport escaped into a nearby watercourse.
Gatwick Airport Ltd has pleaded guilty to a charge of allowing polluting matter to enter the River Mole in September last year.
The prosecution was brought against the company by the Environment Agency after about 5,200 fish of 14 different species died.
Magistrates were told that these were probably three-quarters of the fish in the area.
They were killed after airport staff tried to clear the runway of a seldom-used detergent which had unexpectedly foamed up to create a dangerous, slippery surface, the court heard.
A water hose was used to clear the foam so planes could safely land.
The unintentional result that the liquid flowed into the River Mole to the south of the airport, via Crawters Brook.
Gatwick Airport Ltd faces a fine of more than £20,000 after magistrates referred the case to Lewes Crown Court for sentencing.
They decided their powers, which allow them to impose a fine only up to £20,000, were insufficient.