Profuse growth of aquatic vegetation that often changes the colour of water body is known as:

The rapid, profuse accumulation and growth of microscopic algae or aquatic phytoplankton that directly changes the coloration of a water body (often turning it green, red, or brown) is explicitly called an algal bloom. While eutrophication is the broad ecosystem process of nutrient enrichment that drives this growth, the visible coloration phenomenon itself is denoted as an algal bloom.