The water quality in Qionghai Lake Basin is affected by pollutants like COD, ammonia nitrogen, total nitrogen, and total phosphorus, mainly from non-point sources. Water quality in the lake has been medium eutrophication level, with TN and TP being the main pollution factors. The worst pollution was found in the outlet area of the lake during 2004-2006. To improve water quality and the environment, suggestions include optimizing industrial structure, treating pollution sources, conserving ecology, and enhancing supervision of the environment.