Water quality experts call for metaldehyde ban

There should be at least a partial ban on the use of the pesticide metaldehyde on agricultural land because of its effect on water catchments, industry experts said at the WWT Drinking Water Quality conference yesterday.

Metaldehyde, a chemical used in the majority of slug pellets, is very difficult and costly to remove from water and so presents a significant challenge for the water sector. The conference in Birmingham heard from catchment managers at water companies who had persuaded farmers to use alternative pellets based on ferric phosphate, alternative techniques for killing slugs such as raking and dessication, or to make other changes to their farming practices to minimise surface run-off.

However, several speakers also said that their ought to be targeted bans on metaldehyde use in sensitive catchments in order to get the message across quicker to farmers and speed up progress on the issue.

Thames Water’s water quality and compliance manager David Reynolds said “We’re relying on this partnership approach, but will it work? We have been using carrots – but do we need to start talking about sticks?” He added that catchment management combined with controlled abstraction was “very successful when there is enough water,” but in times of shortage he feared there were “not enough tools in the armoury.”

Anglian Water regional quality manager Robin Price echoed this and said that with alternatives available in the form of ferric phosphate, an Environment Agency-enforced ban would enable the industry to “move on” from the issue of metaldehyde and address the wider picture on pesticide use.

However, other speakers pointed out the practical difficulties of such an approach. An outright ban on metaldehyde would be problematic as agriculture is the not the only user of the chemical, and the diffuse nature of metaldehyde pollution in water would make targeted bans difficult to administer.

Environment Agency drinking water manager Nick Cartright said: “If you start drawing lines saying in this field is in, this field is out, then experience suggests that individuals will challenge those decisions and some will appeal. There needs to be a high level of scientific evidence to back that up.”

National Farmers Union drinking water quality lead Nicola Dunn argued against regulatory intervention, saying that constructive partnerships with farmers were the way forward. “At the NFU we see regulation as a blunt tool for fixing problems,” she added.

The WWT Drinking Water Quality Conference was held in Birmingham on 27 September in association with Northumbrian Water and Veolia Water Technologies.

This article first appeared on wwtonline