What is an EIA? An environmental impact assessment (EIA) is an assessment of the possible impact-positive or negative-that a proposed project may have on the environment, together consisting of the natural, social and economic aspects. The application of this technique is considered as a means of ensuring the likely effects of new development projects on the environment are fully understood and taken into account before development is allowed to proceed. The importance of this management tool is to foresee potential environmental impacts and possible problems caused by proposed project..