Eutrophication in inland waters is an environmental problem that is increasing globally, and its causes should be analyzed in order to reorientate policies on water management in each specific local situation. Global warming and related hydrological changes are intensifying these occurrences of nutrient build up in waterbodies. The associated appearance of harmful algal blooms of toxic phytoplankton is a special ecological problem and is also leading to an increase in treatment costs for water destined to be potable water.  The Water Program of the Inter-American Network of Academies of Sciences (IANAS) calls attention to the need to address this management problem by governmental authorities and institutions involved in water management as it is an important health and environmental issue that needs the introduction of measures to mitigate and reverse the effects of eutrophication.