There are other environmental problems connected with offshore oil, besides oil pollution, many of them are a routine part of operations. In drilling an offshore well, operators customarily discard overboard their drill cuttings with some un-separated drilling mud (which is not actually mud but a combination of clay and chemicals). Atypical 15,000-foot well usually produces more than 1,000 tons of drill cuttings. In addition, mineral salts, which may have distinctly harmful effects on some forms of marine life, are released from geological formations and are regularly discharged after treatment in the course of the production. Localized short-term impacts have been detected as a result of these discharges. Routine discharges like these, together with chronic low-level oil leaks, present “considerable environmental risk,” the Council on Environmental Quality concluded in its report on OCS oil and gas. Digging channels for service ships and barges, building docks and other structures at the waterfront, and, to a lesser extent, laying pipeline cause another kind of environmental disruption. Instead of poisoning marine creatures, these activities tend to bury them, choke them, or cut off the light, which is essential to their whole food chain. Most importantly, dredging and filling change drainage patterns of estuaries and wetlands and can lead to erosion or saltwater intrusion. Increased salinity of the water in marshes and estuaries is usually damaging to the young fish, shellfish, and other organisms residing there. They may not be able to tolerate the higher salinity or they may be decimated by invading predators with an affinity for saltier waters. There are other environmental problems connected with offshore oil, besides oil pollution, many of them are a routine part of operations. In drilling an offshore well, operators customarily discard overboard their drill cuttings with some un-separated drilling mud (which is not actually mud but a combination of clay and chemicals). Atypical 15,000-foot well usually produces more than 1,000 tons of drill cuttings. In addition, mineral salts, which may have distinctly harmful effects on some forms of marine life, are released from geological formations and are regularly discharged after treatment in the course of the production. Localized short-term impacts have been detected as a result of these discharges. Routine discharges like these, together with chronic low-level oil leaks, present “considerable environmental risk,” the Council on Environmental Quality concluded in its report on OCS oil and gas. Digging channels for service ships and barges, building docks and other structures at the waterfront, and, to a lesser extent, laying pipeline cause another kind of environmental disruption. Instead of poisoning marine creatures, these activities tend to bury them, choke them, or cut off the light, which is essential to their whole food chain. Most importantly, dredging and filling change drainage patterns of estuaries and wetlands and can lead to erosion or saltwater intrusion. Increased salinity of the water in marshes and estuaries is usually damaging to the young fish, shellfish, and other organisms residing there. They may not be able to tolerate the higher salinity or they may be decimated by invading predators with an affinity for saltier waters.