Dianchi Lake also serves as the sink of urban sewage, industrial
wastewater and agricultural runoff (Xu et al., 2006). With the rapid
development of economy and urbanization, the lake has been
severely polluted for the past several decades. According to China’s
surface water quality standards (GB3838e2002), the water quality
was at level II, or drinkable with regular treatment, before the early
1970s; now, the water quality is at level V, or undrinkable without
intensified purification. The lake is now suffering from high
eutrophication. Along with eutrophication, the proliferation of
water hyacinth is now a severe environmental problem, clogging
navigation and reducing the amenities provided by the lake.