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Evaluation of the use of detention ponds to mitigate transfer of pesticides to surface waters via drainflow - PS2247

Environment Agency monitoring data demonstrate an intransigent problem associated with the presence of pesticides in river systems. This documented presence presents issues for treatment and supply of water against the 0.1 ìg/L standard for pesticides in drinking water. It also means that many drinking water protection areas (DrWPAs) are either failing or at risk of failing Article 7.3 of the Water Framework Directive which stipulates that there must be no increase in the requirements for treatment of drinking water.

There are various routes of entry for pesticides to surface waters including point (e.g. storm water from farmyards and filling areas) and diffuse (drainflow, surface runoff, spray drift) sources. It is known that a significant proportion of pesticide present in many UK waters arises because of subsurface drainflow. Despite significant research to investigate measures to reduce pesticide transfer to drains, there are no available mitigation measures to prevent these transfers other than product substitution, reduction in application rate or changes to the timing of application to avoid the main drainflow period. Attention is thus turning away from stopping pesticides entering drainflow and towards removing pesticide from water thereafter. Detention ponds have been deployed successfully in the USA and Europe to intercept insecticides and macronutrients in surface runoff. However, it is not known how effective ponds will be under the high-flow conditions typical of sub-surface drainage or in removing relatively mobile pesticides from flow.

The proposed research will evaluate the efficacy of detention ponds for mitigating pesticide transport under conditions typical of UK arable agriculture, particularly where there is significant underdrainage. The study will (i) assess the effectiveness of individual ponds, and (ii) assuming that ponds are effective as anticipated, establish the baseline for a larger-scale study to assess pond effectiveness in reducing pesticide loads landscape-wide. Work will be undertaken at the Game & Wildlife Conservation Trust’s Loddington site where detention ponds have been in situ for at least six years with the aim of controlling sediment and nutrient transport while simultaneously benefiting wildlife. This allows the study to compare the relative performance of established ponds with those more recently installed. Monitoring will evaluate efficacy of ponds in reducing transfer of four pesticides known to be important contaminants of surface water. Work will take place over two successive seasons. The target pesticides will have a range of properties to inform policy about the generic efficacy of detention ponds. The project will deliver evidence on the viability of detention ponds for use as part of the farm management toolbox.
The aim of this research is to evaluate the efficacy of detention ponds for mitigating pesticide transport under conditions typical of UK arable agriculture, particularly where there is significant underdrainage. The specific objectives are to:
1. Evaluate the ability of detention ponds to reduce concentrations of target pesticides reaching surface water via drainflow;
2. Determine how efficacy in removing pesticides from drainflow varies with age of detention pond; and
3. Establish the baseline for a larger-scale project to assess the effectiveness of landscape-wide installation of detention ponds in reducing pesticide loading to surface waters.
Project Documents
• EVID4 - Final project report : PS2247 Final report   (1540k)
Time-Scale and Cost
From: 2011

To: 2014

Cost: £377,660
Contractor / Funded Organisations
University of York
Agriculture and Water Quality              
Diffuse Pollution              
Farm Management              
Pesticide Residues              
Water Framework Directive              
Fields of Study
Pesticide Safety