Just a few years ago, Karanji lake in Mysuru was considered to be one of the dirtiest spots in the city.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/mysuru-green-makeover
[2] http://admin.indiaenvironmentportal.org.in/category/author/sonali-acharjee
[3] http://admin.indiaenvironmentportal.org.in/category/newspaper/india-today-new-delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/karnataka
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/mysore-t
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/lake
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/environment-management
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/green-spaces