Cantareira system reservoirs (São Paulo, Brazil): are the sediment and water impaired with high levels of nitrogen and phosphorus?

• Grant number: 13/04195-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2013
• End date: June 30, 2014
• Field of knowledge: Biological Sciences - Ecology
• Principal Investigator: Marcelo Luiz Martins Pompêo
• Grantee: Natália Abdalla Martins
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The Cantareira System is one of the main public systems of water supply in the São Paulo Metropolitan Area (SPMA). It is a complex system, compounded of six reservoirs interconnected by tunnels. The water quality of the reservoirs upstream affects the quality of the water that reaches to the last reservoir of the system, the Paiva Castro. The great importance of this system is due to two main factors: it provides water to about half of the population that lives in SPMA (9 million of people) and the quality of its water is better than the water of other reservoirs used to the public supply of SPMA. However, there is evidence of deterioration in quality of these waters, attributed to the dumping of organic material,mainly observed in Paiva Castro. This reservoir shows signs of compromise in the quality of the water that reaches from the Atibainha reservoir because it has been applied copper sulfate in the exit of the water of the tunnel, downstream the Juqueri river in hotter periods of the year in order to control the algae growth. Therefore, the increase in the quantity of nitrogen and phosphorus released in the System may be considered the main cause of this algal growth, potentiating the effects of artificial eutrophication. The present study aim to characterize the water and sediment in different points of each of the six reservoirs that compound the System, especially concerning to the nitrogen and phosphorus concentrations, so it is possible to identify the actual situation of each reservoir and facilitate discussions about possible future actions for the control and maintenance of a good water quality.