An agricultural college has been fined £50,000 for causing the deaths of more than 1,500 fish when cow slurry polluted a stream.
Water containing the slurry was spread as fertiliser on a field managed by Plumpton College, in Lewes, East Sussex, in 2016.
It then ran into Plumpton Mill Stream via ditches and drains.
Hove Crown Court heard the pollution in 2016 was classified as a Category 1 incident by the Environment Agency.
The college, which had pleaded guilty at an earlier hearing to contravening the requirements of an environmental permit, was ordered to pay costs of almost £45,000.
The Environment Agency said the college "did not report the pollution had occurred, and nor did it have an emergency plan in place for dealing with slurry spillage".
It said the stream smelled strongly of slurry and the watercourse was visibly brown with foam on the top.
Many of the dead fish were protected species, such as migratory trout.
The college admitted the incident was the result of a mistake by a member of staff and that the actions taken were wrong as the weather conditions and field were not suitable.
Ed Schmidt, environment management team leader in Sussex for the Environment Agency, said: "Poor management, a lack of contingency planning and inadequate infrastructure at the farm resulted in a totally avoidable pollution incident that had a disastrous effect on the local environment."
Plumpton College said the judge's finding supported its own investigation that it was "attributable to an inexplicable course of behaviour by an ex-member of staff who left the college in 2017".
"Judge Barnes supported the college's view that the incident was not indicative in any way of the college's current performance and standards and indeed praised the significant progress made over recent years," it added.