These grades were further boosted by the recent upgrading of the sha tin and tai po sewage treatment works , which meant that the exported treated sewage flowing through the kai tak nullah was cleaner than ever before . egrets have now returned to the nullah , which is teeming with fish once again 由于近年来沙田及大埔污水处理厂进行改良设施后，处理过的污水达到前所未有的低污染水平，启德明渠的水质等级更进一步改进，使明渠内再有鱼类栖息，鹭鸟重临。
As a local public enterprise , the bureau of sewerage supports the cycle of water in tokyo in order to maintain a healthy environment and facilitate normal urban activities . the bureau is responsible for public sewerage management including disposal and treatment operations in the ward area . in the tama area , the bureau manages river based sewerage systems by treating sewage emitted by public sewer systems in local municipalities 作为一个地方公营企业，下水道局支撑着东京的水循环，为了保持一个健康的环境，方便正常的都市生活和协调的都市活动，下水道局既负责特别行政区区域的污水排放和处理事务也负责多摩地区的从市町公共下水道流出的污水处理的流域下水道事务。
