The water utility company pleaded guilty to to one charge of causing a water discharge that was not authorised by an environmental permit.
It was fined £600,000 and ordered to pay £24,000 in costs.
Leeds Crown Court heard how the Environment Agency investigated the incident at Walton Colliery Nature Park in October 2013.
It is understood sometime on or before 05 October, a rising main sewage pipe from the company's Shay Lane pumping station burst and raw sewage flowed into Drain Beck, which feeds a fishing lake in Walton Park which itself flows into the Barnsley Canal.
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More than 860 dead fish were removed from the lake and the canal.
The court heard that there had been four bursts on this rising main in the previous two years, and on each occasion Yorkshire Water had put the failure down to age deterioration of the pipe.
It is understood it will be a number of years before the lake fully recovers to its pre-incident condition.
Mark West, environment management team leader at the Environment Agency, said: "Utility companies have a responsibility to properly manage their infrastructure and ensure that their operations do not put the environment at unnecessary risk.
"This pollution incident had a significant impact on the ecology of the lake and the canal and it could have been avoided had the company taken action to replace the pipe following earlier bursts.
"Aside from the devastating loss of fish, this incident has had an impact on the lake that will last for some time."
(LM)
