Physical barrier to reduce WP mortalities of foraging waterfowl

White phosphorus (WP) has been identified as the cause of mortality to cert ain species of waterfowl at Eagle River Flats, a tidal marsh in Alaska, use d as an ordnance impact area by the U.S. Army. A blend of calcium bentonite /organo clays, gravel, and binding polymers was tested for effectiveness as a barrier to reduce duck foraging and mortality. Following the application of the barrier to one of two contaminated ponds, we observed greater duck foraging and higher mortality in the untreated pond and no mortality in the treated pond after a year of tidal inundations and ice effects. Emergent v egetation recovered within a year of treatment. Mrp levels in the barrier w ere less than the method limit of detection, indicating no migration of WP into the material. Barrier thickness remained relatively stable over a peri od of 4 years, and vegetation was found to be important in stabilizing the barrier material.