Has Government Water Protection Policy Taken Effect On Preventing Harmful Algal Blooms In Erhai Lake?

As the second largest freshwater lake in Yunnan Province of China, Erhai Lake has suffered harmful algal blooms (HABs) since 1996. In January 2017, Dali government issued a series of ecological protection measures to prevent the outbreak of HABs. In order to evaluate the effectiveness of those protection measures, we studied the spatio-temporal distribution of HABs in Erhai Lake by using multi-source remote sensing data during 2016-2018. The results demonstrate that coverage area and frequency of HABs occurrence were decreasing after January 2017, which indicates a good respond to water protection regulations. However, in 2018, HABs still occurred around residential and tourist area. Furthermore, drastic measures also impeded local economic development due to shuttering businesses and banning fanning around lake. Therefore, there is still a long way to go for local government to achieve long-tern goals of sustainable economy and water environment stability of Erhai region.