The present study investigated the evolution of the contamination of the estuary of the Caeté River by thermotolerant coliforms over the past decade. The hypothesis tested was that the conditions of the Caeté estuary have worsened over this period due to a combination of population growth and the lack of investment in public sanitation by the local authorities. Samples for hydrological and microbiological analysis were collected at eight sample points in 2013, 2014, 2018, and 2019. The upper sector of the estuary was represented by the samples from P1–P4. This sector is the most urbanized, and the most affected by human activities, with 100% of the samples collected presenting thermotolerant coliform concentrations of over 1,100 MPN 100 mL⁻¹. Conditions were also considered to be “inappropriate” for human use in other areas at certain times of year. Despite being located within a protected area, the implementation of a public sanitation system, proposed in the master plan of the municipality of Bragança almost two decades ago, has yet to be initiated. Compared with the results of previous studies of the Caeté estuary, more than a decade ago, the contamination of the water has increased considerably. Based on the criteria of the current Brazilian legislation, all types of human use of the water are compromised, although socioeconomic activities continue as normal. This situation may eventually impact the health of the local population and affect economic activities. The conditions found in the Caeté estuary appear to be typical of other coastal Amazonian municipalities.

本研究调查了过去十年中耐热大肠菌群对卡埃特河河口的污染演变。检验的假设是，由于人口增长和地方当局缺乏对公共卫生设施的投资相结合，Caeté河口的状况在此期间有所恶化。在2013年，2014年，2018年和2019年的八个采样点收集了用于水文和微生物学分析的样本。河口的上半部分由P1-P4的样本代表。该部门是城市化程度最高，受人类活动影响最大的部门，收集的样本中100％的耐热大肠菌群浓度超过1,100 MPN 100 mL ^-1。在一年中的某些时候，其他地区的人类使用条件也被认为是“不合适的”。尽管位于保护区内，但大约二十年前在布拉干萨市总体规划中提议的公共卫生系统的实施工作尚未开始。与Caeté河口先前的研究结果相比，十多年前，水的污染已大大增加。根据巴西现行法律的标准，尽管社会经济活动照常进行，但人类使用水的所有类型均受到损害。这种情况最终可能会影响当地居民的健康并影响经济活动。Caeté河口发现的条件似乎是其他沿海亚马逊城市的典型情况。