Antimicrobial resistance (AMR) can disseminate through effluents from seafood processing facilities (SPFs), posing environmental and public health risks. This study assessed changes in coliform load and antimicrobial resistance patterns in effluents from two SPFs in Tema, Ghana, before and after upgrades to effluent treatment systems between 2022 and 2024. A total of 19 effluent samples were collected per SPF in 2021–2022, 20 effluent samples each per SPF in 2024, and 8 potable water samples each per SPF in 2024. Median coliform counts declined significantly in both facilities (SPF-1: 920 to 35 MPN/100 mL; SPF-2: 280 to 9.5 MPN/100 mL; p < 0.001), representing a 96% overall reduction. Escherichia coli prevalence decreased markedly in SPF-2, although Pseudomonas aeruginosa emerged after treatment upgrades. Resistance to third-generation cephalosporins and multidrug resistance declined, particularly in SPF-1, but persisted across both facilities. Potable water used for seafood processing showed low but detectable coliform contamination. Despite substantial reductions in coliform bacterial load, the continued presence of resistant gram-negative bacteria highlights the need for sustained AMR surveillance, mandatory effective effluent treatment, and routine disinfection of potable water to protect public health.