A composition and methods of its use, the composition comprising: a halogen source, urea, and an additional halogen stabilizer excluding urea, optionally an alkali in a concentration sufficient to provide said composition with a pH of greater than 10; and optionally excluding a stabilized bromine compound from said composition is disclosed. Additionally, a method for reducing biological activity in a process stream is disclosed. The method comprises: providing a composition to a process stream, wherein said composition contains: a halogen, urea, and an additional halogen stabilizer excluding urea, optionally an alkali in a concentration sufficient to provide said composition with a pH of greater than 10; and optionally excluding a stabilized bromine compound from said composition. The invention is also directed to compositions and methods of their use as effective biocidal agents for water streams.