Assessing and managing the risk of groundwater pollution by nitrates with the precautionary principle

Groundwater pollution risk may be underestimated because of uncertainties in its assessment, leading to insufficient groundwater protection. This possibility calls for the application of the Precautionary Principle, which requires to adopt suitable countermeasures for preventing the risk of pollution, even if the level of such risk is uncertain. Uncertainty, though, makes it difficult to quantify how much a countermeasure prevents risk and should, therefore, be considered precautionary. What is more without a numerical expression for the level of precaution it is hard to include the latter in quantitative risk management procedures, such as cost/benefits analyses of risk reduction actions. This paper illustrates a promising approach for solving these difficulties, by exemplifying a method for precautionary assessing and managing the risk of groundwater pollution by nitrates coming from agricultural activities. The concept of precaution is interpreted so as to obtain, through risk assessment, a numerical parameter - the precaution degree – which quantifies how much precautionary it is to assign a risk level to an area or how effective, from the point of view of precaution, are different pollution prevention actions aimed at limiting the amount of nitrates used for fertilization. Quantitative cost/benefits analyses of such actions, involving the precaution degree, are also exemplified.