The 51 km-long Najafgarh drain (named after Mirza Najaf Khan 1723–82) starts at Dhansa and joins the Yamuna river just downstream of Wazirabad barrage.

Sanctuary has helped in the improvement in water quality, restoration of groundwater recharge and in providing wetland for the migratory birds.

[9][12][13] Yamuna, from its origin at Yamunotri in Himalayas to Wazirabad barrage, travels 375 kilometres (233 mi) by carrying "reasonably good quality" water.

Between Wazirabad and Okhla barrage, 15 drains discharge sewage rendering the water quality after Wazirabad barrage severely polluted with biochemical oxygen demand (BOD) values ranging from 14 to 28 mg/L and high coliform content.

[14] Causes of pollution are municipal disposal sites, run-off from the commercial and industrial sites, soil erosion resulting from deforestation occurring to make way for agriculture along with resulting chemical wash-off from petrochemical fertilizers, herbicides, and pesticides.