This paper presents results of bacteriological investigations concerning coastal seawater and sandy sediments in the Three-city region at the outlet of four streams: Kacza (KaS), Swelina (SwS), Grodowy (GS) and Kamienny (KmS). The numbers of facultative psychrophilic bacteria, mesophilic bacteria and indicator bacteria (coliforms, fecal coliforms, fecal enterococci) were determined. It was found that all streams are carrying fecal bacteriological pollution of human and animal origin which contributes to poor quality of coastal seawater and sandy sediments. The lowest sanitary quality was KaS water, where the number of all indicator bacteria, as a rule, exceeded admissible levels. In sandy sediments of the estuaries of all four streams the average number of indicator bacteria was about one order of magnitude higher than in water. Enterococcus was the bacterial indicator that exceeded single water or sediment sample standards most often.