This thesis is a history of man’s and nature’s relationship, with regards to water. It is an environmental history about the changes in the wetland landscape around the Lakes Hjälmaren and Kvismaren in central Sweden during the 19th and 20th century. Hjälmaren, Sweden’s fourth-largest lake, was lowered between 1878 and 1888. The lake was lowered 1, 3 metres and the fluctuation of the water level was reduced to 0, 6 metres. The lowering of the lakes Hjälmaren and Kvismaren made it possible to convert 19 000 hectares of wet meadowland into fields for modern agriculture. A dramatic shift in the valuation of wetlands has occurred during the research period. In the 19th century these areas were looked upon as impediments and vast areas were drained and thousands of lakes were lowered. In the late 20th century wetlands are now being regarded as valuable and are sometimes even restored. The first part of the thesis covers the drainage of the area. The shift from traditional agriculture towards modern, market-oriented farming initiated the great drainage project that changed the landscape of the flatlands in the research area. An elite wanted to change the land use. They wanted to drain the meadows so they could be used as agricultural fields. The second part is about maintaining the land for agriculture and again solving the water problem of the region. This was caused by upstream drainages and the lowering of the land. Around 1950 the drained land had sunk about one meter. The solution was dikes and pumps for protection of the agricultural land. The third part of the thesis is about wetland reconstruction to create habitats for wetland birds. The birdwatchers had become an important group in the research area at the end of the 20th century. Two smaller areas were reconstructed and were given statuses as nature reserves, the Kvismare area and the Os, a part of Hjälmaren close to the city of Örebro. In the thesis the water system and wetlands are seen both as a context for actions and a result of these actions. At the centre of the analysis in the thesis is the concept landscape system. The landscape system includes technical solutions, society and nature. Man is around as the active intentional transformer of the system. The term landscape system also includes both thoughts of and regulations as to how this system could, and should be designed. The parts of the landscape system all have seamless internal relations. All groups of actors, the big estate owners, the investigators of flood protection and bird watchers have had to make compromises and gather institutional recourses together with others to reach their goals; to make changes in the landscape system.