The disclosure relates to improved methods for inhibiting the formation and deposition of sulfide and silica scale in aqueous systems. In particular, the methods include injecting a composition into an aqueous system or wellbore. The composition includes a sulfide scale inhibitor and a silica scale inhibitor. The sulfide scale inhibitor may be a copolymer of acrylic acid or methacrylic acid and an anionic monomer. The silica scale inhibitor may be a copolymer of acrylic acid or methacrylic acid and an alkoxylated monomer.