(n.) Drilling Fluids. A test intended to indicate the presence of free oil whendrilling fluid, drilled cuttings, deck drainage, well treatment fluids, completion and workover fluids, produced water or sand or excess cement slurry are discharged into offshore waters. Two types of sheen tests are mandated by EPA under NPDES permits. The visual sheen test consists of an observation made when surface and atmospheric conditions permit watching the ocean water for a sheen around the point where the discharge entered the water. When the conditions do not permit visual observations, a static sheen test is mandated by NPDES permits and the protocol published by US EPA. This test uses sea water in a shallow pan (not more than 30 cm deep) with 1000 cm²surface area. Either 15 cm³ of fresh mud or 15 g fresh cuttings are injected below the surface of the water. An observerwatches for up to 1. 0 hour for a silvery, metallic, colored or iridescent sheen. If sheen covers 50% of the area, the mud or cuttings cannot be discharged. See: Emulsion Mud, EPA, Minerals Management Service, MMS, Mysid Shrimp, NPDES, Oil Mud, Sheen, Synthetic-Base Mud