AP Photos For many Chicagoans, the revival this week of the nearly 60-year-old tradition of Plumbers Union Local 130 dyeing the Chicago River green for St. Patrick’s Day — a surprise event after it first was canceled by the city — was a welcome sign that things are returning to normal. However, was dyeing the river green ever “normal” to begin with? When this tradition began in 1962, the Chicago River, after a century of horrific environmental abuse, was thought of as more a quasi-sewer than a living river. By the late 1970s, fewer than seven species of fish could be found in the r...