Heavy metals are dangerous pollutants for ecosystems, especially aquatic ecosystems, because of their concentration in certain living organisms and their presence in the food chain. This study aims to evaluate the bacteriological, metallic (Pb, Cd, As) and toxicological risks associated with houin logbo (toho lake) in the municipality of Lokossa. The results obtained concern everyone: Toho lake is contaminated by Escherichia coli and faecal enterococci, concerning the evaluation of the metallic contamination we have: