maintenance dredging operations and up to 10 years if an oil spill occurred in the channels or canals. Spills in coastal waters would represent an acute, localized, and low-level impact. Marine waters could be degraded from bottom disturbances, oil spills, and waste discharges. Bottom disturbances could result in minor, temporary impacts due to sediment resuspension. Most oil spills should be small and should affect only small areas for a short-duration. Spills greater than 50 bbl should be infrequent. b. Impacts on Air Quality In Alaska, there could be increases of NO, concentrations and concentrations of other pollutants, but in no case should these exceed the National Ambient Air Quality Standards. Increased concentrations of pollutants evaporating from spilled oil are predicted to be less than from normal operations and last a short period after emissions cease. In the Gulf of Mexico, emissions of pollutants into the atmosphere should have concentrations that would not change onshore air quality classifications. Overall, the air quality status in the Gulf of Mexico should not change because of the emissions from the proposed program. In Alaska, sublethal effects could occur to local populations of the bowhead whale each year due to noiseproducing activities. Noise should affect no more than 20 percent of fin and humpback whales and no more than 10 percent of right, blue, sei, and sperm whale populations each year. Oil spills could affect up to 10 and 5 percent, respectively, of these species' populations. None of the above sublethal impacts should affect recruitment or distribution of these species. Most individuals exposed to oil could experience temporary, sublethal effects, and a few may die. Few bowheads should contact oil. The population is expected to recover to prespill levels within 1 to 3 years. The primary effects on beluga whales in Alaska should come from noise and disturbance, especially icebreaking activities, and other marine-vessel traffic and oil spills. Noise and disturbance could temporarily displace or interfere with movement within a few miles of the activities. Few beluga whales are likely to die from contact with oil spills. Routine exploratory and development activities could displace minke whales from a few square kilometers of summer-feeding areas. No mortality of minke whales is likely as a result of accidental oil spills. Any changes in numbers or distribution should last no more than a few months. An oil spill occurring in the vicinity of one or more major rookeries in the Western Gulf of Alaska in summer, where sea lions are relatively concentrated, is likely to contact up to 50 percent of the local population. Although substantial adult mortality is not likely to occur, considerable pup mortality and adverse effects on juvenile survivorship could result, accelerating the current population decline and requiring more than three generations for recovery. There could be a decrease in fur seal productivity and an increase in existing pup mortality. In the vicinity of the Pribilof Islands in summer and fall, during peak passage of migrants through Unimak Pass and at San Miguel Island during the breeding season, oil spills from tankers could result in losses requiring three or more generations for recovery. Where densities are lower, mortality should be less and thus require only a generation for the population to return to its initial status. |