>> diaz: today in chicago, it's that time of year again. to celebrate st. patrick's day's day crews died the chicago river green. the electrician started when plumbers were detecting leaks with dye that turned water bright green. now a city electrician, the plumbers union dyes the river every year for st. patrick's day. they say the dye is environmentally safe but its ingredients are a closely guarded secret. when we return, the musicians who strike up the madness in march.