You don't need to worry about the slugs. All you have to do is drag a string of empty beer cans [like behind a car at a wedding] the clanking will scare then off. As fare as the empty lakes that is why we use beer cans. The prosessed beverage with the extra nitrates is taking some of the roughness out of the alkaline. No one mentioned the west side lakes especially the urban ones like Green and Angle. But you only want to go on week days and don,t bother going till 4 P.M, That is when all the cars are gone.