On 26 March 2007 a rainstorm started in the area around Rosario. With few interruptions, the rain continued for about a week. Rosario is traversed by the Ludueña Stream in the north; its southern border is partly defined by the Saladillo Stream. The Ludueña has historically been prone to overflowing, which has prompted the construction of works (canals and piping) to contain and derive its waters. Soon after the beginning of the rain, the Ibarlucea Canal (which empties into the main course of the Ludueña, overflowed and flooded several neighbourhoods in the northwest of Rosario. At the peak of the crisis, on 31 March, about 4,000 people were evacuated in several emergency centers throughout the city.