The Najafgarh drain or Najafgarh nalah (nalah in Hindi means rivulet or storm water drain), which also acts as Najafgarh drain bird sanctuary, is another name for the northernmost end of River Sahibi, which continues its flow through Delhi, where it is channelized, and then flows into the Yamuna. Within Delhi, due to its channelization for flood control purposes, it is now erroneously called "Najafgarh drain" or "Najafgarh nullah." It gets this name from the once famous and huge Najafgarh Jheel (lake) near the town of Najafgarh in southwest Delhi and within urbanized Delhi. It is the Indian capital’s most polluted water body due to direct inflow of untreated sewage from surrounding populated areas. A January 2005 report by the Central Pollution Control Board classifies this drain, with 13 other highly polluted wetlands, under category ‘‘D’’ for assessing the water quality of wetlands in wildlife habitats.
This drain was widened as a flood control drain linking the Najafgarh lake to the river Yamuna, thus completely draining the once huge and ecologically rich Najafgarh Lake, famous for its wetland ecosystem, waterbirds and wildlife.
Classification and naming
Within the National Capital Territory of Delhi (NCT), this channelized waterway—misclassified, misnamed as a mere drain (Najafgarh drain or nullah)--is, in fact, the continuation of the Sahibi River and an elongation of the Najafgarh jheel Lake. During the 1960s and before, the rain-fed Sahibi River, which originates in the Jaipur District of Rajasthan, passing through Alwar District in Rajasthan and Gurgaon District in Haryana, entered Delhi near Dhansa and spilled its overflow in the Najafgarh Lake basin. This overflow created a seasonal lake; an area of more than was submerged in some seasons. This water then continued to flow on the other side, forming a tributary of the River Yamuna. In the following decades, this Sahibi River flow reaching the Dhansa regulators was channelized by digging out a wide drain and connecting it directly to the River Yamuna. This channelization also completely drained off the seasonal Najafgarh Jheel that had formed there previously. The channelized drain from Dhansa regulators to Keshopur Bus Depot on Outer Ring Road is wide with thick and high embankments. A vast amount of water is retained in this widened drain by closing the Kakrola regulators under Najafgarh Road to recharge the local ground watertable; hence it acts like an elongated lake as well.
Bird sanctuary and wetland
Wetland ecosystem and wildlife habitat important to migratory waterbirds and local wildlife
The drain has been much widened over the years to drain all the water which in earlier decades used to collect in the Nagafgarh Jheel basin; this was supposedly done to remove the threat of flooding in Delhi and now the drain itself acts as an elongated water body or lake with trees planted on both its embankments with an inspection road running on one embankment. During the winter months it attracts vast numbers of migratory birds and also supports local wildlife year-round. Due to the rich wildlife observed in and around the less polluted stretch of the drain outside of congested populated areas, it has been proposed as a bird sanctuary for Delhi.
The wetland ecosystem and wildlife habitat on several kilometers of less polluted Najafgarh drain in rural Delhi before entering the main city including the former Najafgarh lake or Najafgarh jheel area is very important habitat to migratory waterbirds as well as local wildlife and has been earmarked to be declared a bird sanctuary for Delhi. The area came to be recognized as an important wildlife habitat after a local naturalist studying the area during 1986–88 called attention to it recommending it to be conserved as a bird sanctuary after which the Delhi wildlife department posted 16 guards in the area to control illegal bird hunters including diplomats from various international embassies located in Delhi, India's capital. Delhi Administration officials were tasked with declaring about stretch of the drain in rural Delhi, including where it passes through the core area of the now drained Najafgarh Lake, "protected" under the "Wildlife Act" after Lt.-Governor of Delhi Mr. H.L. Kapur was invited to the area for touring the site where he also heard accounts of local villagers about the rampant illegal hunting of waterbirds that went on here every year. The existing staff of the Flood Control and Irrigation Department numbering about 40 were also given the additional responsibility of protecting the wildlife on and around the drain.