I used to fish Leech lake a lot back in the mid to late 80's and made it there once last year in late June. From my experience the fishing usually started turning on around mid June depending on the temperature. As the temperatures increase the fishing slows. The lake is not that deep and the aquatic plants get pretty thick. I wouldn't call the brookies that inhabit the lake trophies by any stretch of the imagination but they are very pretty looking fish. If you are lucky you might catch one around 12"-13" but most are around 7"-8". My favorite fly to use at Leech is a damsel nymph but pretty much anything you have in your flybox will work.
Leech is fly fishing only. However, there is a 5-fish limit with no minimum size but only 2 can be kept over 12". Also, no motors allowed. WHat is that rule combination all about? Why make a lake FF only and have a 5-fish limit? That seems real odd to me.
The reason there is a five fish limit on leech is because brookies can over populate a lake pretty fast and when there are to many trout there growth gets stunted like in other alpine lakes. If there were less trout in leech they would get bigger. My friend caught a 16" incher out of leech last year and I caught plenty of 8 to 12 inch brookies and also saw a few jump in the 14 to 16 inch range. When I am up at leech lake I catch and release but If I were going to keep any trout I would do so at leech lake to help the population and because brookies taste good.Oh and because you can only keep 2 over 12 inches and 3 to 5 under 12 inches is because they want to thin out some of the small fish for the reasons above. :THUMBSUP