In 1575, the viceroy Toledo ordered to build several artificial lagoons east of the city that would be useful to accumulate water during the rainy season, with the intention of using them in the dry periods. The artificial lagoons of Potosi are considered to be one of the main elements of the mining infrastructure. These lagoons are located in the Eastern part of the city. They were constructed in almost 50 years and with the participation of 20,000 indigenous residents. A large wall was built as well at the Northern end of the city to take advantage of the city's natural slope, to retain the water with greater ease and to use this construction as a dam. This helped to get a greater better motive power from the water kept in these construtions. The first lagoon was called "Chalviri", which was used to construct the main dam. In 1576 the digging of the "Kari Kari" Lagoon began, which has also been known as "San Idelfonso", "Chalviri" and "San Sebastian".