High-performance oil spill response sediment control products. Since 1975, ABASCO has been a recognized leader in oil spill response equipment. ABASCO turbidity curtains (also called turbidity barriers, silt curtains, or silt barriers) contain the silt and sediments stirred by in-water or near-water construction activities and by dredging operations. Our turbidity control specialists will help you conform to all regulations and requirements that might apply to your project, including the Clean Water Act, National Pollution Discharge Elimination System (NPDES), and state (DOT) and local regulations.