Rotenone last longer the colder the water. A week or so when temps are in the 50's. In AL in August you may be able to put fish in the next day. Use a test fish to see if water is safe. I'm sure you know this but rotenone is a restriced use pesticide and you will have to have a certified commericial applicator do this for you.

WHy the heck are you waiting until August? As Shan mentioned you can rotenone now and still put in all your fish this year if you do it right. Why not use the time you have the lake drained to fix the leak on the dam.

Greg Grimes
www.lakework.com