According to this recent comparative analysis of the environmental achievements, challenges and priorities of Indian states, north-eastern states are most-sustainable and the least sustainable states are Bihar, Haryana, Gujarat, Punjab, Rajasthan & Uttar Pradesh.

Latest comparative analysis of environmental achievements , challenges and priorities among Indian states. Provides overall picture of state-level sustainability by aggregating data on states

The Environmental Sustainability Index report for 2008 by Centre for Development Finance tracks the environment performance of 28 states and projects their ability to protect the environment in future. Manipur leads as the best performing state followed by Sikkim and Tripura.