tough time of year for fly fishing,early morning late evening might be the best bet,I suggest hiking up one of the many streams along the shore as they are all stocked,not sure if the fishery is still open at the french river but if it is stop in and chat with the dnr personel they can fill you in on more details.
Also look to slack water for feeding activeity later in the day for suface feeders,water will be high after all the rain the shaore has had lately.