The water at IGL is top notch.
BUT...that exact topic is becoming a huuuuuge problem for the Lakes area and it's already started impacting the economy up there and the surrounding area. It's gotten too clear.
Zebra mussels have taken hold on East/West 'Boji, Lower and Upper Gar, and Center Lake. Spirit Lake will be in the same boat soon. The water clarity is off the charts due to the mussels and fishing has become a whole lot more difficult in most places East Okoboji has become almost non-traversable by boat in the summer now because the clear water has allowed underwater vegetation to go absolutely bonkers. Some months it looks like you can walk on top of the water and people can't even use their boat docks because of it. Property values are going through the floor but people are still paying five digits a year in property taxes that are probably worth half what they were 6-8 years ago.
Ice fishing at any of the IGL has always been world class. Tons of fishing shows filmed up there every year. We were out on Emerson and Triboji this past winter and we could see a 4mm ice fishing jig on the bottom in 25' of water. It's terrible. Fishing when the water is like that is all but impossible because those fish are super, super spooky. You need that water to be at least somewhat murky. It varies day-to-day, but for the past two years you can mark all the fish you want on your sonar but good luck getting a consistent bite. I've been fishing for 38 years so I feel pretty comfortable saying it's not me. Lots of other guys say the same thing. It's gotten to the point where I'm considering selling off all but the most necessary pieces of ice gear because it can be such a hit or miss thing. You can go up one day and limit out, but then you can have 2 or 3 garbage days in a row where you work your ass off for just a few dinks. Ice fishing is way too much work for that.