The familiar murkiness of waters in the Gulf of Mexico can be off-putting for beachgoers visiting Galveston Island. Runoff from the Mississippi River makes its way to local beaches and causes downstream water to turn opaque and brown. Mud is one factor, and river runoff is another. However, concern tends to ratchet up a notch when pollution enters the river runoff discussion on a national scale, specifically when smaller, navigable intrastate bodies of water push pollution into larger interstate waters often involved in commerce (i.e. the Mississippi River, Great Lakes, Ohio River).