Baixo Mondego, PT
The Portuguese case study consists of two contiguous river basins, the Lower Mondego and the Lower Vouga valleys. Groundwater for public drinking is extracted from aquifers upslope of the more intensive agriculture and husbandry on the plains. However, many farmers in the rural areas of Lower Mondego have wells that they use both for irrigation and drinking water.
The main contamination problems occur in the dry summer season and are caused by excess nutrients being added to the soil in the form of ammoniac nitrogen and nitrates. Manure and wastewater sludge are increasingly being added to the soil as fertilizers. This is compounded by the impact of poor intensive husbandry management that contaminates both aquifers and superficial water bodies. Consequently 42% of the aquifers have nitrate concentrations above the national average. Some surface water bodies also seasonally exceed the limits for several drinking water pollutants.
The soils this area are also being used as a medium to dispose of organic waste within a circular economy strategy that aims to close energy and matter loops at the local scale. However, this is not done without risk, and the addition of residues to the soil has to be controlled in order to keep under the legal pollutant concentration limits for both ground and surface water, all year round and particularly during the summer dry period.
Objectives are to:
- limit the concentration of nitrate to 50 mg NO3/l in superficial water bodies and groundwater in the agricultural area;
- limit the concentration of each individual pesticide to 0.1 µg/l and of total amount of pesticides to 0.5 µg/l in superficial water bodies and groundwater in agricultural areas;
- establish a participatory governance framework to discuss strategies and practices and implement best solutions in a swift way, involving all stakeholders in a common plan of action.
Targets for agricultural management are to assess:
- the impact of cropping systems and establishment of application thresholds for the soils in the two study areas;
- to what extent alternative cropping systems and crop management techniques (organic farming, integrated pest control) can improve or worsen nitrogen and pesticide pollutant concentrations and control.