During the last decade, international farmland investments have increasingly grown in developing countries. This contribution aims to highlight the environmental implications of these investments on freshwater resources within the Niger River Basin. In particular, international farmland investments put a dilemma between the sovereign right of States to use their lands and the obligation to protect transboundary aquatic environment. The article will emphasize these environmental implications and suggest the minimum standards needed to guarantee an environmental friendly agro-investment. Such standards will be drawn from the Niger River Basin innovative legal framework which makes of the protection of environment a cornerstone of the management of the River Basin.