The heavy discharge of industrial effluents has severely affected aquatic fauna at the Ramsar site, set up in River Ganga in 165 km stretch from Bijnore to Narora in Uttar Pradesh.

Ramsar sites are a tag for critical water bodies across the globe.

Discharge of toxic wastes such as methane has led to decline in the population Gangetic dolphins from 126 to only 28 in the last five years. The site was set up by the World Wildlife Fund in 2005 for the protection of water bodies from getting contaminated, wildlife officials said.

Besides the decrease in dolphin numbers, officials have also recovered bodies of many fish species, crocodiles and tortoises.

"Dolphins which were 126 in 2005 have reduced to only 28 now due to contaminated water. Population of many fish species also reduced in this period," district wild officer Jaswant Singh said.

About 35 villages in the area have also been affected due to water poisoned by the alleged discharged from an industrial unit of the Simbhaoli sugar mill into the fresh water, near Ghaziabad district, officials said.

Two notices have been issued to the industrial unit and the mill-owners were asked to recycle the water, UP Pollution Control Board Regional Manager Tu Khan said.

However, General manager of the unit R K Singh claimed the methane discharge is within permissible limits.

District Magistrate Hredesh Kumar said an inquiry will be conducted in this regard by the sub divisional magistrate Som Dutt and strict action will be taken if the mill owners are found guilty.