The objective of this study was to evaluate water seasonality in the process of granting permits and the impact of irrigation in the Dourados River basin. For that, the hydrological behavior of the basin was analyzed. The minimal streamflows (Q.sub.7,10 and Q.sub.95), irrigation withdrawal flow (Q.sub.r) and the percent variation of the grant flows relative to monthly seasonal period in relation to the monthly withdrawal flow were obtained. The results allowed to verify that using criteria based on the monthly streamflow allows for better management of water use, because it allows for greater utilization of this resource in times with high water availability and imposes a realistic restriction during critical periods. The average annual water withdrawal for irrigation in the basin during the studied period was on the order of 2.99 m.sup.3 s.sup.-1, and the withdrawal flow in the month of highest demand (August) was 5.95 m.sup.3 s.sup.-1. Key words: water resources hydrological behavior water management O objetivo deste trabalho foi avaliar a sazonalidade hidrica no processo de concessao de outorga e o impacto da irrigacao na Bacia do Rio Dourados. Para tanto, procedeu-se a analise do comportamento hidrologico na bacia. Foram obtidas as vazoes minimas de referencia (Q.sub.7,10 e Q.sub.95), vazoes de retirada pela irrigacao (Q.sub.r), e variacao percentual das vazoes de outorga relativo ao periodo sazonal mensal em relacao a vazao de retirada mensal. Os resultados permitiram constatar que a concessao de outorga de uso dos recursos hidricos quando adotada a escala mensal garante um plano melhor de utilizacao da agua, a medida que permite seu uso no periodo em que ha disponibilidade hidrica e restringe no periodo de escassez hidrica. A vazao media anual de retirada pela irrigacao na bacia no periodo em estudo, foi da ordem de 2,99 m.sup.3 s.sup.-1, sendo a vazao de retirada no mes de maior demanda (agosto) de 5,95 m.sup.3 s.sup.-1. Palavras-chave: recursos hidricos comportamento hidrologico gestao da agua