A common belief today is that environmental protection and studies of pollution started in the 1970s. This is understandable. Environmental studies have focused on the past 20-30 years, not on the past century. Environmental politics have been studied mostly on a governmental level, not on a municipal level. The impact of green movements has been studied, but the role of urban residents, politicians or professionals in environmental politics has been neglected. Most of the studies on environmental history have concentrated on the history of the protection of nature in the countryside. Cities have rarely been studied in environmental history despite the fact that 80% of inhabitants in the Baltic Sea region, for example, live in urban areas.

It is argued that the municipal network of wastewater treatment plants in Northern Europe is the oldest, largest, and most effective sector of environmental protection. The cities created the ideology and practices of environmental protection between the end of the 19th century and the 1960s, consisting of urban environmental movements, research and development programmes, economic planning schemes and infrastructural reform programmes. It is claimed that this development was a precondition for the transformation of urban environmentalism to a national and governmental phenomena in the 1970s. As a result the contemporary network of municipal wastewater treatment plants has improved the state of our environment more any other single innovation. However, this goal has been achieved only by intensive technical and natural scientific research, expensive investments, and hard – and sometimes lost – political battles. Clean urban and coastal waters are taken for granted today. Effective wastewater purification networks and the monitoring of the water courses are considered to be commonplace in all developed countries.