One of the environmental constraints on oil and gas development on the North Slope of Alaska has to do with the need for causeways. Causeways have been used to support docking facilities, drilling and production facilities, and waterflood sea water treatment plants. The design preferred by industry is a solid-fill, gravel causeway. Many governmental permitting and resource agencies feel that the environmental effects of this design are unacceptable. Two solidfill gravel causeways have been built in the vicinity of Prudhoe Bay. It has been found that some alteration to circulation patterns and localized, temporary changes in nearshore fish habitat results from the presence of these structures. While some fear that this puts the fish populations at serious risk, no effects on the local fish population have been found. Nevertheless, other, more expensive and technically unproven (in Arctic) options, such as subsea pipelines and bridge type structures, have been proposed, as environmentally preferred alternatives. These should be site specific decisions. The increased difficulty in obtaining permits for gravel causeways may result in not being able to develop some nearshore reservoirs.