hi Mickem, I did some research on Shilongba and realised that...

hi Mickem, I did some research on Shilongba and realised that aside from being a reservoir, it is also oldest hydro power station in China.

This is the answer to your question:

”A probe by local environment authorities found that two of three chemical plants upstream on the Tanglangchuan river were covertly discharging acidic wastewater into the Dianchi lake, which supplies fresh water to the power plant. The chemical units were fined 50,000 and 60,000 yuan and the pollution control board of the Kunming Environmental Bureau ordered them to suspend operations till they improve production processes, reports Xinhua, the state news agency. Meanwhile, green groups are demanding tougher actions against polluters.”

https://www.downtoearth.org.in/news/water-pollution-threatens-chinas-oldest-hydropower-station-8750
article was dated July 2015.

In saying that, I did a similar search on Baidu maps (Chinese google) and the lake came up turquoise colour, not that milk white in your Google. I’d imagine images taken at different time. It would be a seasonal/ occasional occurrence.

i can’t get the satellite imagine on my phone- see if you can click and figure out how to turn the map view into the satellite view which is possible on a desktop.
https://map.baidu.com/mobile/webapp/place/detail/qt=ninf&wd=石龙坝水库地图&c=104&newmap=1&from=alamap&tpl=mapdots&uid=e3e2cd9d4f027ce0c7f50dc3&industry=scope&qid=3479454610639161108/showall=1&pos=0&da_ref=listclk&da_qrtp=11&da_adtp=&da_log=&da_adquery=石龙坝水库地图&da_adtitle=石龙坝水库&da_adindus=自然地物;水系&vt=map