Paul Monfils wrote, If salinity in excess of 6 parts per thousand kills them, I wonder if they could be controlled by seeding the beds with rock salt?? Theoretically the large, heavy rock salt crystals should sink quickly, with minimal dissolving on the way down; then dissolve on the bottom, creating a dense bottom layer with salinity well over 6 parts per thousand; then gradually diffuse into the overlying water, causing negligible increase in salinity to the main water mass?? What do you think? ++++++++++++ Well, Paul, for starters, the zebra mussels wouldn't die right away. After all, they are adapted to live in fluctuating conditions at the mouths of rivers. They would probably just clamp their valves shut until the salty water was diluted or flushed away. Also, what else are you willing to kill just to control the zebra mussel? Six parts per thousand is equivalent to brackish water, which would assuredly kill most species of native freshwater mussels, and just about everything else adapted to fresh water, including plants. If you killed off the zebras' (admittedly feeble) competition, the prolific zebras would soon bounce back with higher populations than ever. In Alabama, when drillers for coalbed methane proposed to dump very slightly salty (but drinkable) water into the Cahaba River, environmentalists landed on them like a ton of bricks. But please don't stop posting your ideas. They are always stimulating. Andrew K. Rindsberg Geological Survey of Alabama