For many industries and municipalities in California, biocontrol problems have traditionally been solved using sodium hypochlorite bleach solutionsThe reasons for this are obvious: sodium hypochlorite is inexpensive and efficacious.On the other hand, in many circumstances, indiscriminate use of sodium hypochlorite can have a devastating impact on the environment in terms of it contributing high levels of sodium chloride and undesirable disinfection byproducts into discharge waters.This paper documents several California case studies where biocontrol using sodium hypochlorite was not an option because of these adverse properties.In particular, the use of peroxyacetic acid (PAA) as an environmental-friendly alternative to sodium hypochlorite is highlighted.Firstly, the phys. and chem. properties of peroxyacetic acid (PAA) solutions are reviewed and compared to those of sodium hypochlorite bleach solutionsThe decay profile of PAA dosed to a variety of different water matrixes is presented along with the results of a study addressing the impact of PAA applied to a Central Valley sandy loam soil.Examples where the favorable environmental properties of PAA have been successfully exploited are described and include: - Municipal wastewater disinfection without the formation of chlorinated disinfection byproducts.- Cooling water disinfection without the need for sulfite dechlorination of the discharge.- Algae control in reclaimed water lagoons used for land irrigation without contributing to soil sodicity and salt-induced phytotoxcity to grass.- Slime control of surfaces in California canneries without the formation of pungent chloramine odors.- Control of mold and yeasts in California wineries without the worry of tainting the wine with unpalatable 2,4,6-trichloranisole.