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002~94 high sustained releases that followed the BHBF and inundated previously drier habitats. As with the earlier flood, a 2-day 45 k flow will once again bury the grass / herb layer in New High Water zone patches below 40 kcfs. This layer, made up of herbs and perennial grasses for the most part, as well as some seedlings and saplings of larger species, has shown some recovery in the past two years, given the high summer flows which promote growth. The nutrients in these habitats, mostly locked up in plant tissue, will not be mobilized, since the plants will be buried in place. Larger woody individuals will have some bark and branches (and leaves if the flows occur much after Aprill) stripped during the flows, but there will be little uprooting or outright mortality directly attributable to the flows. Assessment: will negatively affect riparian vegetation (but the effects will be less than spectacular) . Similarly, the soil seed bank will be buried again under sterile sand from the channel bottom and elsewhere in the eddy complex. As with the grass / herb layer, the soil seed bank has shown some remarkable signs of recovery in the past two growing seasons. A two- day 45kcfs flood will likely cause another loss on the order of 60% of the individuals and 40% of the species present in New High Water zone vegetation patches. Assessment: will negatively affect the soil seed bank. Marshes in return current charmels will likely be buried under - 50 cm of sediment again, and green plants will likely be knocked over and flattened. The effects will depend on the timing and subsequent flows. Assessment: will negatively affect the marsh vegetation, but flows before mid-April will hilVe less impact than those after (the investment in green tissue will be lost), and if high flows follow the flood, the impacts will be less visible after 6 months. Impacts on riparian habitat follow the above assessments. LITERATURE CITED Aldrich, l.W. 1951. A review of the races of the Traill's flycatcher. Wilson Bull. 63(3): 192-197. Aldrich, J.W. 1953. Habitats and habitat differences in two races of Traill's flycatcher. Wilson Bull. 65(1): 8-11. Arizona Game and Fish Department. 1996a. Ecology of Grand Canyon backwaters. Final Report to U.S. Bureau of Reclamation, Glen Canyon Environmental Studies, Flagstaff, AZ Arizona Game andFish Department, Phoenix. Arizona Game and Fish Department. 1996b. The effects of an experimental flood on the aquatic biota and their habitats in the Colorado River, Orand Canyon, Arizona. Arizona Game and Fish Department, Phoenix. Ayers, A.D., and T. McKinney. 1 996a. Lake Powell forebay and Glen Canyon Dam tailwater to Lee's Ferry during interim flows: particulate organic matter transport, nutrient