Pig slurry overflowed a storage lagoon and polluted a stream in Howsham, Scunthorpe Magistates’ Court heard last week.
Lee Warner and James Edward Andrews, trading as Lincolnshire Pigs, pleaded guilty to polluting the stream, which leads to the Froghall Drain, in March 2010.
Warner was fined £1,500 and Andrews was fined £2,500.
Full costs were awarded to the Environment Agency and each defendant was ordered to pay £2,459.
The two were accused of failing to follow good farming practice. They failed to regularly empty the slurry storage lagoon, leaving it for more than six months, said Miss Claire Bentley, prosecuting for the Agency.
She told the court that the partners devised contingencies to follow should the lagoon become too full, but none of the measures was adopted.
She said “The discharge could have been prevented if good farming practice had been followed.”
As a result, 1.8km of the stream was polluted and macro-invertebrates were severely affected.
Miss Bentley told magistrates that clean water and dirty water from the lagoon was not kept separate and pollution checks of surrounding surface waters were inadequate.
“Integral checks of the lagoon were never carried out so the defendants did not know what the capacity of it was,” she said.
The pollution was reported to the Environment Agency on March 2 2010 and traced by officers to Lincolnshire Pigs’ site at Cotswold Farm.
In a corner of the farm they saw a ditch flowing from the farm boundary into the main stream, which had been dammed twice with wooden boards.
Effluent flowed around and under both dams. At another place along the boundary, earth had been piled high to block the flow of slurry over the top of the lagoon bank.
On March 23 an officer discovered that in another corner of the farm a manure pile was leaking liquid, which escaped into the ditch through its weeping wall.
It looked as if it had been dammed off downstream, said Miss Bentley.
Warner told investigating officers that he did not realise that the polluted ditch was linked to the stream.
He said that emptying of the lagoon depended on the availability of farm land on which to spread it and rainfall.
Emptying of the lagoon had been delayed because of wet weather which also meant they could not spread earlier.
Since the pollution he said they had emptied the lagoon in April and had planned to clean it out to increase storage space.
Andrews told investigating officers he knew the lagoon was getting full so a week before the incident he blocked the slurry channels into it, which normally gave them a two-week leeway. At the start of March they dammed the ditch as a back-up in case it overflowed.
Miss Bentley told the court that an Environment Agency biologist concluded that the gross pollution had severely affected the macro-invertebrate fauna in the stream for 1.8 km.
Ammonia levels in the sample were 769 mg/l whereas in unpolluted waters the level would normally be less than 1 mg/l.
She told the court that Andrews had a previous conviction for three similar offences from 2008.
After the hearing Environment Agency officer Anna Ganiford said: “We hope this prosecution will send a message to other operators that poor practice is unacceptable and pollution prevention matters.
“Pollution like this can have devastating effects on the watercourse and it is essential that all care is taken to prevent this type of incident.”