OPDEP HC 144 (U.S. Coast Guard) The OPDEP HC 144, also known as the Oil Pollution Detergent Dispersant Effectiveness Procedure, is a standard test method developed by the United States Coast Guard for evaluating the effectiveness of oil pollution dispersants in breaking up and reducing the thickness of oil slicks on water. The test procedure simulates real-world conditions to assess the performance of these dispersants under various environmental factors. It plays a crucial role in the prevention, response, and recovery efforts for oil spills, ensuring effective response actions can be taken promptly.