Improvement of the ecological situation in the Russian regions leads to the creation of new economic instruments of regulation in this sphere, such as environmental taxes. However, the introduction of new forms attracts attention to necessity of tools that reflect the current situation and efforts of the municipal system. The importance of the concept of sustainable development and the need to consider environmental factors at the municipal level are substantiated, the methods of weighing indicators to construct indexes are summarized. The article proposes the approach to the formation of ecological effectiveness performance index for municipal system of Nizhny Novgorod region, based on the analysis of existing approaches to the construction of composite indicators, and requirements on the feasibility and applicability in practice (taking into account the existing limitations of information gathering).The advantages and limitations of this approach are shown; recommendations on modification of the index (with consideration of features of particular region municipalities) are given.