The Araruama Lagoon (Rio de Janeiro) is known for its scenic beauty and natural resources, factors that have led to the economic expansion of the region. In recent decades, tourism and property speculation have been key to the urban development of the municipalities surrounding this Lagoon. Using secondary data and a theoretical framework based on Political Ecology and Critical Environmental Education, this article seeks to analyze the correlations between the development processes of the towns surrounding the Lagoon and the impact of these processes on the environmental quality of its ecosystem. In recent years, the evolution of parameters studied revealed that the imbalance in terms of the sustainable development of the region has damaged the health of this body of water. Large quantities of fresh water, as well as domestic and industrial effluents discharged without appropriate treatment in the Lagoon, have overloaded the ecological system, with negative effects for the entire economy in the surrounding area.