Bulletin 19 - March 1983: History of the Abu Dhabi Sewage Farms

History of the Abu Dhabi Sewage Farms

A small sewage farm commenced operation in September 1973 to separate solid matter from partially treated water. Situated on the eastern side of Abu Dhabi Island, the site was adjacent to the so-called Eastern Lagoon, just to the southeast of the Defence area. The number of filtration beds and tanks were increased in 1976 to treat the sewage from a rapidly-expanding Abu Dhabi. By the end of 1982, however, the area was being used only as a pumping station and for treated water storage. The main treatment plant is now at Mafraq.

In 1973 there was no commercial use for the treated water, in contrast to the present when most of the recovered water is recycled to irrigate parks and afforested areas. Formerly the water was released into a flat muddy area of mangrove and saltbush vegetation near the Eastern Lagoon. The water contained a low organic content of solids which were deposited on the previously saline marshland. A beneficial cycle using oxygen and carbon dioxide developed. Bacteria in the sludge broke it down to form nutrients, which in turn were consumed by algae. To complete the cycle the algae took in carbon dioxide and in turn released the oxygen required by the bacteria. The resulting interdependent ecosystem created a local environment favourable to the expansion of existing vegetation and the introduction of new species such as Lippia nodiflora, Typhus domingensis, Frankenia pulverulenta, Scirpus maritimus, Malva parviflora and Anagallis arvensis.

Many of these species became locally dominant in the fresh water area. How they managed to arrive at the sewage farm in the first place remains a mystery, but some were presumably introduced as seed by the wind or even on the feet of birds.

The area rapidly developed into perhaps one of the finest fresh water marshes in the Gulf region. By late 1976 the area was a haven of plants, insects and algae for migrating birds. Many first sightings were made on the marsh, which was unique on the north-south migration routes from Russia to East Africa. It served as a resting place sometimes for many thousands of birds, from small passerines and waders to larger raptors. Some, such as the Graceful Warbler and Kentish Plover, nested in the vicinity. There was little disturbance, except by the odd youngster out shooting or a falconer trying to ensnare a passing saker or peregrine falcon.

In late 1978 came the first rumours that the sewage farm was to be moved. It was not large enough to cope with the human traces (as Martin Willmot, Traces Recorder, would express it) generated by the population of Abu Dhabi. This was followed by news of a proposed eastern corniche and a dredged channel to back-fill the area. There was talk of preservation and conservation, but in reality once planners have planned it is very difficult to unplan. The area was manmade and is now being man-destroyed. Without a constant flow of fresh water it would have gradually reverted to its former status as salt marsh.

Many of us resolved to get the maximum from the area while it still lasted and to record as many visiting birds as possible. A few stalwarts have made at least weekly visits, ignoring the occasional bad smell and mushy footholds. Progress, alas, has almost caught up and the new corniche is rapidly devouring the main marshy area. The pumping of salt water from the foundations of nearby buildings has killed off most of the fresh water vegetation, and with it the habitats necessary for the wellbeing of temporary migrants. There is still a wealth of birdlife to be seen, but it now consists almost entirely of seabirds and waders, although there are the occasional passerines and birds of prey. It is sad that the area will become residential rather than a place where mere humans could commune with nature. Well kept parks sprayed with insecticides will never have the same attraction for migrating birds.

The new sewage farm is situated in a valley on the Al Ain side of the Mafraq flyover, close to Jarn Yafour. It is expected eventually to treat some twenty million gallons of water a day, much of which will be returned to Abu Dhabi to maintain the luxuriant growth of shrubs and plants in parks and central reservations. The new airport site will take up to three million gallons a day.

The creation of a new farm area will result in additional locations for birds to rest and seek food. Although finding and recording them will be more difficult, hopefully the benefit will be for the birds. At the airport, however, it could increase the possibility of bird strikes.

Occasional misfortunes sometimes work out for the best. Early in 1982 a mechanical fault led to the dumping of many millions of gallons of treated water into a dune area to the southwest of the new sewage farm. This created a lake two kilometres long, half a kilometre wide and in places several metres deep. The present might seem an ideal time to think in terms of a conservation area. The lake level may rise and fall but it is reasonable to assume that some water will always be there. With rainfall and increased pumping rates, the signs are hopeful. With careful planning and planting, the region could become an ideal study area for younger generations of UAE citizens and amateur scientific groups such as the ENHG to study natural history and bird migration.