Lakes with steep bottom lines aren't the best ones for chronie fishing. Ones with flats and better yet... mud flats are the ones that produce more chronies. I'm assuming your "nids" are what I'd call chronies.

The leech suggestion was best for fishing a deep lake early in the year. Leeches are bigger and better seen or felt by fish... and.... an obvious food source for early in the year. March 1st in the seeps what I usually see in stomach samples are leeches... and the little pindot sized shrimp... or diatoms.... In any case they are about a #32. Leeches would be a very good fly this early in the season.