This paper aims to assess the conditions under which hydraulic projects can be considered as an efficient option, from an environmental point of view, to secure water supply of agricultural areas using the Territorial Life Cycle Assessment (T-LCA) methodology. Firstly, the environmental performance of three theoretical agricultural land-use planning scenarios are defined: (1) a business-as-usual case without irrigation, (2) irrigation with an Inter-Basin Water Transfer (IBWT) and (3) with an Agricultural Reservoir (AR). These are all assessed by computing the territorial eco-efficiency (i.e. a ratio between the services provided by land planning scenarios and their related environmental impacts). Secondly, Territorial Life Cycle Assessment methodology was used to assess the water-energy-infrastructure nexus between the two hydraulic projects. Results indicate that the eco-efficiencies of the scenarios vary according to the service considered and to the type of land use. For land management or economic functions, the scenario without irrigation can perform better, while hydraulic projects are more eco-efficient for functions related to biomass production. The analysis of the water-energy-infrastructure nexus highlights the trade-offs between the two types of project. On one hand, IBWT allows for the use of a low-stress water resource and less energy, but may require high material consumption. On the other hand, AR uses less material while relying on a more scarce water resource. IBWT performs better than AR if the pipe length is less than 100 km, with a water allocation of 1% (proportion of the infrastructure allocated to the considered agriculture area). This study underlines the importance of considering the territorial context in the environmental assessment of land planning projects in order to support decision-making.