LIMeco: Level of River Pollution from Macrodescriptors for the Ecological State

The LIMeco index, introduced by Ministerial Decree 260/2010 (amending the technical standards of Legislative Decree 152/2006), is a descriptor of the trophic state of the river, which considers four parameters: three nutrients (ammoniacal nitrogen, nitric nitrogen, total phosphorus) and the dissolved oxygen level expressed as saturation percentage. The calculation procedure involves the attribution of a score to the concentration of each parameter on the basis of Table 4.1.2/a of Ministerial Decree 260/2010 and the calculation of the LIMeco of each sampling as the average of the scores attributed to the individual parameters, then the calculation of the LIMeco of the site in the year under consideration as the weighted average of the individual LIMecos of each sampling. The calculation of the LIMeco to be attributed to the water body is the average of the values obtained for the three-year period 2010-2012. Where in the same body of water are monitored, several sites the value of the LIMeco is calculated as a weighted average (based on the percentage of body of water represented by each site) of the LIMeco values obtained at the different sites; finally, the quality class is assigned to the body of water in accordance with the limits laid down in Table 4.1.2/b of Ministerial Decree 260/2010. The quality, expressed in five classes, can vary from High to Bad. For the determination of the Eco-State, the LIMeco index does not fall below the Sufficient level.