 É objectivo deste trabalho discutir a génese das políticas de águas e de florestas em Portugal na segunda metade do século XIX. Pretende-se demonstrar que a construção do objecto político de ordenamento de águas e de florestas para a globalidade do território nacional, bem como as políticas de per se sobre estes sectores, se formularam entre 1852 e 1886. This research aims to clarify the crucial role of water and forest policies for territorial management in 19th century, both in Portugal and other European countries. The absence of forest in the slopes eases erosion, loss of biodiversity and provokes increasing torrential flows, responsible for material and vegetative destruction. In the middle of the 19th century, torrential floods became an increasingly problem in Portugal. By then, the State was only responsible for national goods and State properties administration. The connection between forestation and the control of torrential impacts would require an intervention over all property regimes.  This situation led into big controversy. Some defended that public interests should prevail over private property rights in order to prevent natural catastrophes while others refused to increase such an amount of power to the Public Administration. That would endanger the system of economic activities and citizenship freedoms, rights and warranties, granted by those prerogatives. Only by the end of the 19th century, water and forest administrative laws - covering all property regimes- were approved in Portugal - and I argue -, in France, Spain and Italy by similar reasons.  Like two centuries ago, urges the need for better coordination between political decision-making and the introduction of legal framework on water and forest management. To develop efficient environmental policies in Europe it has been required in the past and it should be adopted nowadays, a similar or common cross border regulation, considering ecosystems instead of political boundaries. Therefore, this work contributes for better understanding of natural disasters re-merging due to climate changes and draws the attention for the possibility of controlling that negative impact through adequate political decision. 