Nanhu Lake – Abstract – Nanhu Lake, Yueyang City, Hunan Province, People’s Republic of China

Application Report

Place: Nanhu Lake, Yueyang City, Hunan Province, China

Date: 6 June 2018 – 11 June 2018


Nanhu Lake, ~12 km2 in size (3,000 acres), an inner part of the Dongting Lake, is located in Yueyang City, Hunan Province, China. The lake is a key recreational attraction, and serves the ~6 million residents of Yueyang. Toxic cyanobacterial blooms started plaguing Nanhu lake in 2008, with their frequency and severity worsening ever since. The blooms are attributed to decades of pollution from man-made sources (agricultural and aquaculture runoff, sewage discharge, etc.).

 The results are conclusive:

The targeted treatment of the Lake GuardTM Blue product for mitigation of cyanobacterial aggregates resulted in the collapse of the cyanobacterial scum at the water surface, as seen on both satellite images and drone aerial imagery below.

Satellite imagery processed with Lake GuardTM View presents cyanobacterial intensity levels as a heatmap, scaled from undetectable/low levels (cold colors, blue), to high levels (warm colors, red).

The figure shows significant improvement within 24 hours after the initial treatment, and continued improvement at 5 days post-treatment. Cyanobacterial load in the lake was dramatically reduced, by 70%, from its June 6 levels.

Aerial imagery of the Nanhu lake docking area. (A) June 6, cyanobacterial scum is visible on the water surface. (B) June 9, three days after the initial treatment- cyanobacterial scum is no longer visible on the surface