The hydrochemical character of Lake Xolotlan (Managua) is clearly dominated by sodium bicarbonate, but the lake is also strongly influenced by thermal activities in its coastal and bottom areas which contribute to high concentrations of chlorides and sodium. Lake Xolotlan is endorheic and has a high evaporation rate (2,395 mm per year) which is twice its annual precipitation (1,129 mm). There is an inflow of domestic industrial sewage from the city of Managua. All these factors are subjecting the lake to strong contamination, salinization and eutrofication. The lake can be considered to have an intermediate status between eutrophic and hypertrophic according to measured total-P concentration. Due to high concentrations of some of its ions, the water of Lake Xolotlan cannot be used for irrigation.