Lake Pátzcuaro () is a lake in the municipality of Pátzcuaro, Michoacán, Mexico.
Lake Pátzcuaro lies in an endorheic basin, which does not drain to the sea. A watershed area of 929 square kilometres drains into the lake, of which 126.4 are the water body. The Lake Pátzcuaro watershed extends 50 kilometres east–west and 33 kilometres from north to south. Lake Pátzcuaro lies at an elevation of 2,035 metres, and is the center of the basin and is surrounded by volcanic mountains with very steep slopes. It has an average depth of 5 metres and a maximum of 12. Its volume is approximately 580 million cubic metres.
The Lake Pátzcuaro basin is of volcanic origin. At times it has been part of an open and continuous hydrological system formed by Lake Cuitzeo, Pátzcuaro and Lake Zirahuén, which drained into the Lerma River. Today, like lakes Cuitzeo and Zirahuén, it is a closed basin, although ecologists consider it a sub-basin of the Lerma-Chapala basin. the essentially harmless Mexican garter snake of the subspecies patzcuaroensis, the fish Pátzcuaro chub (Algansea lacustris) and Pátzcuaro allotoca (Allotoca diazi), and the dwarf crayfish Cambarellus patzcuarensis.
The lake and its surrounding wetlands have undergone significant environmental changes over the past 50 years. Logging and agriculture in the surrounding watershed have contributed to siltation of the lake (1 cm / year - 1.2 million cubic meters / year), and water diversion for agriculture and urbanization has reduced the size of the lake by 40 square kilometers, and 2.6 meters in depth. Other threats include untreated sewage, the introduction of exotic species, and chemical pollution.
In February 2021, members of the Supreme Indigenous Council of Michoacán (CSIM) noted that political opportunism, corruption, and a lack of coordination have undermined efforts to clean up the lake. They noted that since 2006 MXN $5 billion has been spent, and since 1934, 2,300 studies have been conducted, yet 79% of the inhabitants of Pátzcuaro, Erongarícuaro, Quiroga, and Tzintzuntzan live in poverty and 40% in extreme poverty.
Watershed
In the watershed surrounding the wetlands, the natural terrestrial vegetation is composed of xeric scrub (1,920–2,100 m above sea level), pine and oak forests intertwined with xeric scrub (2,100–2,400 m) and by pure pine-oak forests in the higher peaks (2,400–2,900 m). The pine-oak forests are part of the Trans-Mexican Volcanic Belt pine-oak forests ecoregion.
In the last fifty years, human activity in the watershed has intensified. Farming and livestock ranching in the basin have significantly increased. Over 10,000 hectares of forest have been lost to logging, fires, fuelwood gathering, and clearance for farming and ranching.