Sunday 20 October 2019

County Limerick fish kill originated on North Cork farm

Bill Browne

Cork County Council has confirmed that silage effluent that leaked from a farm in Milford last May resulted in a major fish kill on the River Deel in County Limerick.

Officers with Inland Fisheries Ireland reported that the incident had resulted in the death of almost 600 fish of various species along a 6km stretch of the river downstream of the discharge, close to the Cork/Limerick border, with most of the dead fish found in County Limerick. 

A spokesperson for the Council said that while action was being taken against the responsible farmer, the farm in question has good silage storage facilities with effluent collection channels and a slatted storage tank. 

The spokesperson said that wet silage had caused a silage pit on the farm to split, resulting in it slipping out past the collection channels and into the nearby river. 

"The farmer co-operated fully with the authorities, (Inland Fisheries Ireland, Limerick City & County Council, & Cork County Council), in controlling the spillage once it was brought to his attention," said the spokesperson. 

"This was an accidental silage effluent spillage which occurred on a farmyard with good silage storage facilities. It demonstrates that even with good facilities it is essential that management is good and that farmers need to be very vigilant in dealing with silage effluent." 

One of the most potent pollutants on a farmyard, silage effluent has a Biochemical Oxygen Demand (BOD), or polluting capacity, of 65,000 mg per litre. This is considerably stronger than slurry at 15,000 mg per litre and raw sewage at 300 mg per litre. 

The spokesperson said it essential that regular checks were undertaken to ensure there was no silage escaping from farms. 

"If silage effluent is allowed to escape to watercourses, it can have devastating consequences for fish, wildlife and for drinking water supplies," said the spokesperson. 

Aidan Leonard, an agricultural scientist with Limerick City and County Council, said all drains and watercourses downstream of the farmyard should also be checked regularly to ensure they are free from contamination.

"Silage effluent is more than 200 times more polluting than raw sewage and, as we have seen, its impact on waters can be devastating. Every year, despite widespread awareness across the industry of the threat from silage effluent leakages, there are incidents of leakage which can cause immense damage to rivers and streams," said Mr Leonard.

Advice to farmers to avoid silage spills

* Ensure that all silage storage facilities are constructed to Department of Agriculture specifications.

* Before cutting silage ensure that effluent tanks are empty.

* Repair any damage or cracks to the silage slab & walls using suitable materials.

* Clean all effluent collection channels and make sure that pipes leading to tanks are clear.

* Lay perforated land drainage piping in the channels around the pit to improve drainage and relieve effluent pressure on floor and walls.

* When the pit is covered, make sure that effluent is intercepted by the effluent channels, and that all clean water off the polythene is directed away to the clean water drainage system.

* Regularly inspect any watercourses downstream of the farmyard once silage making begins. Take immediate corrective action, if any contamination is suspected.

* Ensure that any diversion chambers/points are set correctly to divert effluent into storage tanks.