There were three basic types of gates in the giant slalom races this year: green hanging gates (pass on the left), red hanging gates (pass on the right), and blue 'marker' gates (usually mark eddies, paddler must be 'inside' the imaginary line created by the marker). Touch a gate, add 10 seconds to your time, miss a gate add 50 seconds. Unlike conventional slalom where your whole run through a rapid is dictated by the position of the gates, in a giant slalom the racer has the time and space to choose how they will approach the gates. Some gates have a 'correct' line and some gates can be caught in a variety of ways.
The courses (Little White, NF Payette, OBJ, and Green Narrows) were all set on challenging, but accessible rapids. Basically, if you were comfortable running all the rapids on the river you would be comfortable running the slalom lines. Usually there was one or two mandatory sketchy lines on a given course. For instance, on the North Fork, you had to punch the meat biggest hole in Otter's Slide rapid to catch the gate below the hole.
"A river is more than an amenity, it is a treasure."
-Oliver Wendell Holmes writing for the majority in New Jersey v. New York