Wales' largest dairy farm has been fined £36,000 after cattle slurry waste polluted a nearby stream.
Part of a brook in Carmarthenshire was "80 to 90% covered in sewage fungus", according to officials.
Llanelli Magistrates' Court was told the foaming effluent in Fernhill Brook was near to two farms operated by Cwrt Malle Ltd.
Owners Howell and Susan Richards run the "super-dairy" with a herd of 1,900 cows.
The court heard that tests were carried out by Natural Resources Wales downstream from Cwrt Malle farm, where the stream was "discoloured and foaming, with a strong odour present".
Analysis discovered pollution was well above levels safe levels for oxygen in the water, known as the 'Biochemical Oxygen Demand' or BOD.
Prosecutor John Tarrant said the accepted BOD set by the European Union was a reading of three.
The BOD levels at Fernhill Brook were 5,178.
But while he said while the levels were high, the leaks had not killed any fish nor caused admitted any long term damage.
Mr Tarrant also told the court that Cwrt Malle had previously been fined £5,000 for a similar offence in 2013.
The court heard pollution of the stream happened when a "slurry lagoon" of animal waste overspilled.
Defending solicitor Aled Owen also blamed extremely heavy rainfall.
"It had been the highest rainfall recorded in 100 years," he said.
"This is a very well run and modern farm."
Cwrt Malle Ltd admitted six offences of breaching environmental regulations.
Five of the offences occurred between December 2015 and September 2016 at Cwrt Malle.
The remaining breach happened at Wernolau Farm in January 2016.
As well as a £36,000 fine, the farm firm must also pay £8,500 in prosecution costs.