_____________________________________________________________________________________________________ *Corresponding author: Email: aprilefm@hotmail.com; Asian Journal of Geological Research 2(1): 1-16, 2019; Article no.AJOGER.47050 Hydrogeological Characteristic and the Vulnerability Degree of the Aquifers from Municipality of Abaetetuba, Pará - Brazil Andreza C. M. Leite 1 , Gilmar W. Siqueira 1 , Assad Darwich 2 and Fabio Aprile 2* 1 University of Pará Federal, 66075-100 PA, Brazil. 2 National Institute of Research in Amazonian, 69060-001 Amazonas, Brazil. Authors’ contributions All authors participated of the samples collection, date and statistical analysis and wrote the first draft of the manuscript. Article Information Editor(s): (1) Dr. Ahmed Abdelraheem Frghaly, Associate Professor, Sohag University, Egypt. (2) Dr. Mohamed M. El Nady, Professor, Department of Organic Geochemistry and Petroleum Geology, Exploration, Egyptian Petroleum Research Institute, Egypt. Reviewers: (1) Nordiana Mohd Muztaza, Universiti Sains Malaysia, Malaysia. (2) Ali Mohamed Ali Hamdan, Aswan University, Egypt. Complete Peer review History: http://www.sdiarticle3.com/review-history/47050 Received 05 December 2018 Accepted 21 February 2019 Published 12 March 2019 ABSTRACT This study evaluated the quality of groundwater in the municipality of Abaetetuba (PA, Brazil 1°43'46'' S e 48°52'27'' W) based on the hydrogeological characterization and degree of vulnerability of the aquifer system. The municipality of Abaetetuba is practically all supplied by groundwater both by deep tubular wells and shallow pit wells (Amazonian wells), which present potential risk of contamination. Water and soils samples from 20 wells sampled between 2012 and 2016 were used. Physicochemical and microbiological analyzes served as a data base for mapping (GIS). Three hydrogeological domains were identified within the study area: Barreiras Group (predominant), Post-Barrier Sediments and Recent Sediments. Almost all of the samples presented microbiological levels above the MPV defined by the Brazilian legislation for water intended for human consumption. The DRASTIC and GOD vulnerability indexes presented values between 75 and 119 and 0.15 and 0.32 respectively, suggesting areas of 'low' to 'moderately-high' vulnerability. Local sources of pollution by coliforms have been identified due to lack of basic sanitation. Evidence of diffuse sources derived from vehicle washing and lubrication also have been identified. Although the Barreiras Group had deep semi-confined aquifers, a 'state of alert' Original Research Article