Hove Crown Court was told that management failings at the agricultural college, which pleaded guilty to the offence at Lewes Crown Court last year, caused slurry to pollute a nearby stream significantly.
The court heard that in November 2016, contaminated water containing a high amount of cow slurry was spread as fertiliser onto a field at Wales Farm, now called Lambert Farm, managed by Plumpton College.
Head herdsman Stuart Duncan carried out the work despite the fact that the volume spread was many times more than the field could absorb. As the ground was also frozen, much of the contaminated water ran off into ditches and land drains which then flowed into the nearby Plumpton Mill Stream.
The Environment Agency classified the pollution as a category one incident – its most serious level. 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 court heard that the Environment Agency became aware of the incident after it was reported by a member of the public. The college did not report the pollution and did not have an emergency plan in place for dealing with slurry spillage.
The Environment Agency had been in regular contact to advise the college on its management and operations on a number of occasions since 2011 because of concerns about incidents and non-compliances with agricultural regulations.
The college admitted the incident was the result of a mistake by a member of staff. It conceded the actions taken to spread the slurry were wrong as the weather conditions and field were not suitable. Before sentencing, Duncan accepted a formal caution for his actions contributing to the incident.
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.
“It is even more disappointing that a college that specialises in agricultural practices and teaches farmers of the future, failed to take all reasonable actions and was wholly negligent in preventing this incident from occurring in the first place.
“The outcome of this case should be a clear and strong message to all people working within the farming industry to ensure they think about the actions they take when managing highly polluting liquids.
“Ensure you are compliant with codes of practice and take the time to review your procedures. Consider seeking advice from the Environment Agency or qualified consultants, check and maintain your infrastructure and test your emergency planning and response to accidental incidents.”
Costs of £44,852.66 were awarded against the college, which is based at Ditchling Road, Lewes.