Determining if and when a potential accident scenario is subject to requirements of the National Environmental Policy Act (NEPA) of 1969 has long been an open question. This issue is routinely addressed by some agencies, yet is virtually ignored by others. Certainly, not all federal proposals merit a detailed analysis of accident scenarios. Yet, how does one determine under which circumstances an analysis of accident scenarios should be subject to a NEPA analysis versus those that are not? The implications of this issue are particularly important with respect to low-probability high-consequence events. Beyond the obvious risk of increased exposure to litigation, this question is of interest for other reasons, not the least of which being that such an analysis can substantially increase schedules and cost. This paper examines this question and provides a tool consisting of seven tests for assisting practitioners in reaching a determination.

A study of the benthic invertebrates that inhabit three small streams draining into the Sasyk Reservoir located in southwestern Ukraine was made in the summer of 1995 to assess water quality of the streams. Biotic indices of water quality were compared to chemical analyses of water samples to determine the extent of agreement between biological and chemical water quality assessment. Results of the study indicated that water from the Kogilnik, Fontanka, and Drakula Rivers is highly saline, reflecting high rates of evaporation and leaching of salts from highly saline soils. Runoff from intense agricultural activity in the region enriches the water in ammonia and other forms of nitrogen. Among the chemical variables measured, total salinity appears to be most indicative of water quality. Total salinity in the Fontanka River (2600 mg per liter) was approximately 900 and 2300 mg per liter higher than that of the Kogilnik and Drakula Rivers, respectively. Similarly, the biotic indices obtained for the Fontanka River were lower than those for the other two rivers. The biotic indices suggest that water from all three rivers should not be used for direct human consumption without prior treatment. The use of benthic invertebrates for assessment of water quality is discussed.

Benthic barriers and surface covers installed to control alligatorweed (Alternanthera philoxeroides) suppressed growth after five months in Cane Creek Lake, a water supply reservoir serving the towns of Chapel Hill and Carrboro, North Carolina. By five months, no shoot biomass and few fibrous roots were detected below benthic barrier plots and only white and flaccid shoots and roots were detected below surface cover plots. Phenotypic differences were observed based on the varying duration of coverage. Surface cover and benthic barrier treatments that lasted from one to three months delayed flowering of alligatorweed by one month, while areas covered for four and five months did not flower at all. Shoot lengths were less for shaded treatments compared to control plots. Dissolved oxygen was lower and pH more acidic after one month coverage under benthic barriers. After two months, pH and dissolved oxygen recovered under benthic barriers to values near the control plots. Water chemistry in the surface cover and control plots were similar. Light penetration below benthic barriers and surface covers was blocked throughout the experiment, suggesting no deterioration of the materials occurred after five months placement in the lake. Application of light shading materials gave seasonal control of alligatorweed. Deployment and maintenance of surface covers and benthic barriers were similar and both methods are recommended for aquatic plant management of alligatorweed in Cane Creek Lake.