This review evaluates the knowledge gained from the Demonstration Test Catchment (DTC) programme. The DTC was a government-funded programme, which was designed to provide evidence regarding how diffuse pollution from agriculture can be cost-effectively controlled. The primary aims of the project were to evaluate the knowledge gained on intervention effectiveness for water quality, and farmer engagement. The secondary aim of the project was to evaluate the broader physical and social science methodologies that were adopted, and the approach for generalising the findings. The evaluation was carried out by undertaking a Rapid Evidence Assessment (REA) of the available, published evidence.
The key findings were that DTC interventions can improve water quality, with reported reductions of >80% sediment, >90% for specific pesticides, 75% for nitrate and 50% for phosphorus. However, effectiveness of the interventions depended on scale and intervention type. The implementation of on-farm measures was limited in DTC catchments, this resulted in a change in focus of the project from the effectiveness of measures, to understanding the catchments and collecting a longer baseline. The report recommends that a monitoring programme would need to run over a longer period of time with a greater density of interventions to assess the effectiveness of measures. The report also answers 7 further physical science questions regarding evidence, methodologies, models, and management of the interventions affecting the DTC project. The review found that engagement and awareness raising is necessary, but not sufficient to ensure uptake of measures. This is attributed to the complex series of choices farmers make between becoming aware of diffuse water pollution from agriculture and finally implementing changes on their land. The report also answers 6 further social science based questions regarding methodologies, engagement, behaviour factors, variation, cost effectiveness, and confounding factors affecting the DTC project.
- DTC programme reports can be found by searching the following codes:
- WT15100 [for phase 3 reports]
- WQ0225 [for phase 2 reports]
- WQ0210 [for phase 1 final report]
- WT15116 DTC evidence compendium