In the coastal aquifer of Orange County in California, seawater intrusion driven by coastal groundwater pumping increased the concentration of bromide in extracted groundwater from 0.4 mg l_1 in 2000 to over 0.8 mg l_1 in 2004. Bromide, a precursor to bromate formation is regulated by USEPA and the California Department of Health as a potential carcinogen and therefore must be reduced to a level below 10 mg l_1. This project compared two processes for treatment of highly colored groundwater: nanofiltration and ozone injection coupled with biologically activated carbon that are utilized by two different water agencies in Southern California.