Lake Water Quality 2016-2018 (raster 1 km), global, 10-daily - version 1

Monitoring water quality in lakes and reservoirs is key in maintaining safe water for drinking, bathing, fishing and agriculture and aquaculture activities. Long-term trends and short-term changes are indicators of environmental health and changes in the water catchment area. Directives such as the EU's Water Framework Directive or the US EPA Clean Water Act request information about the ecological status of all lakes larger than 50 ha. Satellite monitoring helps to systematically cover a large number of lakes and reservoirs, reducing needs for monitoring infrastructure (e.g. vessels) and efforts.

The Lake Water Quality products provide a semi-continuous observation record for a large number of medium and large-sized lakes, according to the Global Lakes and Wetlands Database (GLWD) or otherwise of specific environmental monitoring interest.

They consist of three water quality parameters: (i) the turbidity of a lake, that describes water clarity or whether sunlight can penetrate deeper parts of the lake. Turbidity often varies seasonally, both with the discharge of rivers and growth of phytoplankton; (ii) the trophic state index that is an indicator of the productivity of a lake in terms of phytoplankton, and indirectly, over longer time scales, reflects the eutrophication status of a water body and (iii) the lake surface reflectances that describe the apparent colour of the water body and are intended for scientific users interested in further development of algorithms. The visual reflectance bands can also be combined into true-colour images.