About 22% of rivers in the South (8% in the North) are classified as poor or bad quality (Figure 4.3). Groundwater quality shows significant regional differences. For example, in the regions/provinces of Trento, Bolzano, Liguria, Lazio and Marche, between 75% and 93% are classes 1 to 3; in Abruzzo and Umbria, 43% and 32% respectively are class 4 (poor).