Sea quality in the area of Istria has been monitored continuously since 1988. Based on years-long examination, the criteria of sea quality have been introduced, classifying it into four categories marked by different colours. Blue colour marks high quality sea, green colour marks the sea acceptable for bathing, yellow colour marks moderately polluted sea, while red marks heavily polluted sea.
These criteria tend to point out the coastal areas with very clean sea. It is precisely the blue colour that makes the basis of the Blue Flag project which aims at preserving sea and shore. Beaches and marinas with Blue Flags are the ones with clean sea, quality services and equipment, and in order to be recognized as such they have to meet numerous criteria of the sea and shore preservation project which has been implemented in Europe since 1987, and since the year 2000 even in the rest of the world. The award is given for the period of 1 year and has to be earned every year.