This report details the finding of the modelling exercise undertaken to show how changes in nitrate leachate from the different primary Programme of Measures would impact on the nitrate concentrations in the groundwater in the project's eight pilot catchments over a period of time. The modelling demonstrated that in some cases the WAgriCo measures would help maintain and improve the groundwater quality. In other cases because of the effects of the historically leached nitrate it would not prevent exceedance of drinking water quality nitrate standard.