The document summarizes the history of pollution in Montcada, Spain and efforts to clean up the city. It describes how Montcada was once one of the most polluted cities in Spain due to 3 rivers, 6 industrial states, 3 highways, a rail line, and an incinerator. In the 1990s, an environmental group formed to advocate for cleaning up the city. As a result, laws and actions were taken to protect the environment, though Montcada is not fully clean today. A natural park was built alongside one river, and in 2002 a water treatment plant was constructed using a 7 step process to clean Montcada's water.