TWO dairy owners have been prosecuted after 400 litres of cream spilled from a Brighouse dairy into a nearby stream.
The pollution left oxygen levels in the beck dangerously low, Calderdale magistrates in Halifax were told.
Daniel Harrison, and Richard Harrison, both of Smith House Lane, Brighouse, admitted causing poisonous, noxious or polluting matter to enter Hoyle House Beck and Clifton Beck.
Both men were fined £2,500 with £153 costs to the Environment Agency, which brought the prosecution.
The court heard that on November 7 last year a report was made to the agency that Clifton Beck in Brighouse had turned white. Officers traced the source back to Hoyle House Beck and from there to Harrison's dairy on Smith House Lane. Samples were taken both upstream and downstream of the spill.
The magistrates were told that one of the ways the agency can determine water quality is by measuring the amount of oxygen required by micro-organisms to break organic matter - or the BOD (Biological Oxygen Demand).
Bacteria already present in a river will feed off polluting matter, in this case cream, and breed more rapidly, using more oxygen and leaving less for fish and other river life.
Any contamination of a watercourse with a BOD greater than 17mg/litre is described as grossly polluted. Analysis of water upstream of the pollution was 1.5mg/l but downstream it was 3180mg/l. The pollution was approximately 10 times stronger than raw sewage.
In a letter to the agency the dairy said that a delivery of cream arrived there on November 7 and normally it would have been unloaded immediately with a forklift truck, but this piece of equipment had broken down.
As well as this, the unloading area of the yard was blocked by another vehicle so the unloading was carried out in another area of the yard, close to a surface water drain which led directly into the beck.
As the tank of cream was being unloaded, it fell and burst open. The contents flowed into the drain leading into Hoyle House Beck.
In mitigation Daniel Harrison said it was a one-off accident. There was no intention to deposit cream into the beck.
He said the dairy diverted the surface water drain to the appropriate foul sewer.