Sousa, R.C., Pereira, L.C.C. and Costa, R.M., 2013. Water quality at touristic beaches on the Amazon coast.The beaches of the Brazilian Amazon coast are visited by thousands of tourists each year, mainly during the peak summer vacation month of July. Unfortunately, the beaches have been developed without adequate planning and the lack of a public sanitation system results in frequent bacteriological contamination. Given this, the aim of the present study was to verify the bacteriological quality of the water (total coliforms) at three local touristic beaches over different stages of the tide cycle. The campaigns were conducted in July 2009 and 2010 at Ajuruteua, Atalaia, and Princesa beaches. Water samples were collected in the surf zone every 3 hours (7:00–19:00 h), over four days (Friday–Monday). Simultaneously, oceanographic instruments were placed in the surf zone to obtain hydrodynamic data (currents, tides, and waves). The high local hydrodynamic energy is the result of macrotides (> 4.0 m), moderate wave heights (Hs > 1 m), and currents with speeds of around 0.5 m/s. Atalaia has the highest density of bars and hotels, and also presented the highest proportion of contaminated samples (45% > 1100 MPN/100 ml). At Princesa and Ajuruteua beaches there is less urban development and a smaller number of potential sources of contamination (cesspits). Peaks of contamination were recorded during high and ebb tides, when the water level reached the cesspits, although there was a rapid turnover and bacteriological concentrations returned to tolerable levels during the other tidal phases. To improve the local water quality, sewage treatment plants are needed urgently at all three sites.