Back in the 1980s , however , the shing mun river was not for the fainthearted . it was severely polluted from industrial and commercial effluent , discharge from livestock farms , runoff from unsewered villages , and effluent entering through expedient connections in the new towns . its most polluted branches were the tai wai , fo tan and siu lek yuen nullahs , all of whose water quality was consistently graded bad , with black water and foul - smelling sediment 回想八十年代，城门河状况堪虞，区内的工商业污水禽畜废物无污水收集系统的乡村污水和来自新市镇的非法接驳污水渠将污水排入河内，造成严重污染，其中以大围火炭和小沥源明渠的污染情况最为严竣，持续录得恶劣水质等级，河水淤黑而臭气薰天。
