Despite the fact that cephalosporins are rarely used in medical or veterinary treatment, the presence of Enterobacterales strains resistant to this group of anti-bacterial drugs (ESBL) is an important issue that requires attention. Between 2019 and 2021, 14 retention reservoirs, 12 streams, 3 rivers and 1 lake situated in the Tricity area (in northern Poland) were sampled for the presence of ESBL strains. Out of 40 water samples, characteristic growth (E. coli and the KESC group) on Chromagar ESBL plates was observed for 33 samples. The average number of ESBL E. coli was 42±132 CFU/100 ml, while the KESC group was 73±147 CFU/100 ml. Out of 33 positive samples, 57 ESBL Enterobacterales strains were isolated, of which the most abundant species were E. coli (13 isolates) and S. fonticola (23 isolates). The E. coli ESBL isolates not only showed resistance to third generation cephalosporins but also to antibiotics from other groups, such as fluoroquinolones, aminoglycosides and sulfonamides. The S. fonticola ESBL isolates were also found to be mainly resistant to the third generation cephalosporins, with the exception of 5 imipenem and 2 ertapenem-resistant strains. These strains presented highly diverse fingerprinting profiles, as well as significant differences in phenotypic traits helpful for survival in the environment, such as biofilm formation and motility. Moreover, biofilm formation and the swimming ability were species and temperature dependent. We confirmed the presence of highly diverse ESBL strains with multiple drug resistance patterns in the Tricity water reservoirs. This could possibly pose a threat to human health and create a suitable ground for acquiring antibiotics resistance in the natural environment.