Managua waste water to a new water treatment plant at Las Mercedes in Eastern Managua in May 2009 relieved old concerns over water pollution and native wildlife, and brought some residents closer to the old city center and the rest of the mainland. Managua is located on the southern shores of Lake Xolotlán, also known as Lake Managua. Lake Xolotlán contains the same fish species as larger Lake Cocibolca in southeastern Nicaragua, except for the freshwater sharks found exclusively in the latter. Once a Managuan scenic highlight, the lake has been polluted from the dumping of chemical and waste water since
Managua 1927. A new sewer system and the redirecting of waste water to a new waste water treatment plant at Las Mercedes funded by the German government to decontaminate the lake is expected to be the largest in Central America and was inaugurated in 2009. Managua's city area extends about , essentially south from the south shore of Lake Managua. The lakeshore is at an altitude of above sea level, and the city climbs as it gets towards the Sierras de Managua further south where it is over above sea level. Geologically, the city lies on fault lines, thus seismologists predict