A teenage girl causes her friend to laugh as they mess about beside Guanabara Bay. The bay's water, where 70 percent of the city's sewage is dumped, was declared too polluted for swimmers to use in 2001. They now use the parrallel Piscinao de Ramos (big pool of Ramos), an artificial pool built beside the bay by the state of Rio de Janeiro to give North Zone residents clean water to enjoy. It holds 30 million litres of filtered and chlorinated seawater and can attract 80,00 visitors over a single, sweltering hot weekend. Despite its popularity, the piscinao (big pool) is controversial. Some north region residents believe it was built to keep them away from the luxurious south zone beaches. Nonetheless, thousands of people who live in the surrounding favelas visit throughout the summer.