Guajará Bay marks off the city of Belém, capital of the Pará State, in the Amazon Region. It is formed by the confluence of rivers Guamá and Acará. Belém, is full of bays and creeks forming islands all around it; there are 55 of these islets, most of which are wild. Founded in 1616, it was the city from where the occupation of the Amazon Region began. With its privileged position, it is a very important distribution point for products to and from the entire Amazon Region. Belem has the highest population density in the region (about 1,500,000 people); this creates problems for the city’s water and waterworks operators. All the waste waters are discharged into Guajará Bay or River Guamá. A growing level of pollution has been observed on the beaches located in the islands near the city of Belém.