Ecological Impact Assessments are produced once a design has been finalised and informed by the results of protected species surveys (or other ecological constraints) at the site. They aim to identify the important ecological effects that arise as a result of a development proposal, and propose avoidance measures, mitigation detail or compensation to ensure that no significant residual ecological effects arise due to the proposal.

EcIAs can either be completed as part of a formal Environmental Impact Assessment (EIA) process to form part of an Environmental Statement, or as part of a non-EIA project. The EcIA should make it clear to the decision maker what the potential significant effects are, how the effects have been avoided, minimised or compensated for, and whether any significant residual effects remain once these measures have been implemented.