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This paper aims to present the problem caused by the emission of hydrogen sulfide (H 2S) in the Tiete River in the city of Pirapora do Bom Jesus, in Sao Paulo State, and also indicates possibilities to im- prove this problems, from two actions: the first is the treatment of water from the Pinheiros River, where there is the aim to divert approximately 40m³/s of polluted water from Tiete River for treatment at the Pinheiros River; the second is the entry into operation of the Small Hydropower Plant Pirapora. It is expected a signifi- cant improvement for the problem of H 2S emission.

The great urban, industrial and agricultural growth of the cities across the Paraiba do Sul river region collaborates to river contamination. Then it is necessary keeping a more rigid river water quality control, considering its importance for the regional economic development. In this study the spatial and temporal water quality and pollution level were characterized. The evaluation was based on water collects from Taubate region during rice cultivation. The results showed that the practice of rice cultivation favored the increase pollution level of the Paraiba do Sul river. The rice cultivation adduced fertilizer and organic matter into the river showing the need for a water rational management depending on fertilization conduct. Palavras-chave: qualidade da agua, nitrogenio, fosforo, controle de poluicao, cultura do arroz inundado. 1. Introducao A agua e o componente mais abundante encontrado na natureza cobrindo aproximadamente ¾ da superficie da terra. Porem, alguns fatores limitam a quantidade de agua disponivel para o consumo humano tais como, falta de planejamento dos espacos urbanos e industriais, o uso inadequado da agua e a poluicao. O inicio do crescimento industrial no Vale do Paraiba foi de grande importância para o crescimento regional, assim como tambem foi responsavel por grandes impactos no Rio Paraiba do Sul. O crescimento, alem de ocorrer rapidamente, localizou-se principalmente ao longo do eixo do rio, o que facilitou a utilizacao inadequada e abundante da agua e o despejo de esgotos e efluentes. De acordo com a CETESB (2009) a poluicao das aguas e gerada por tres fatores:  efluentes domesticos (poluentes orgânicos biodegradaveis, nutrientes e bacterias);  efluentes industriais (poluentes orgânicos e inorgânicos, dependendo da atividade industrial);  carga difusa agricola e urbana (poluentes advindos da drenagem destas areas: fertilizantes, defensivos agricolas, fezes de animais e material em suspensao).