There are a couple different ways to fish jigs

1. Float fish it
2. fish it without a float, cast and twitch cast and jig or drift it.

You can fish jigs in any river, there is jig water in every river.

There are some die hard jig fishers that only fish jigs and they fish them in all conditions. As with any tool I fish jigs in there time in place, (most of the time in low clear conditions or in water you cannot drift during normal flows).

Jigs can be very effective and I have had some of my very best days using jigs. I have found that jigs are a very important part of my arsinal and I wouldnt leave home without them.