This study fulfils the need of establishing a guideline for environmental conditions that could be used to designing stages in projects submitted to Environmental Impact Assessment (EIA), in order to consider minimal requirements not only to encourage EIA proceedings but also to reduce Environmental Impact Statement (EIS) contents. EIS from the last 10 year for different civil works projects (roads, railways, airports, dams, hidroelectrical power stations, river channelizations, pipelines, water transfers, ports and works in the coast) have been studied, extracting all the environmental conditions found. Effectiveness and real implementations of theses conditions have been analysed in different phases of the project development, which have allowed a characterization of a series of environmental conditions that could improve environmental assessments and authorities’ decisions for EIS.