Before they finish, have them taper the shoreline 4:1 out to a few feet of water depth, then they can go 3:1 out to 6'-8' depth, then 2:1 if the soil will hold that slope. If it's sandy soil, it usually won't stay in place if the slope is steeper than 3:1.
Have the dirt above the waterline 4:1 or less steep to make getting to the water easier.