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.- v 00 r- (~ production ponds that have not established full densities or C~ mature root and tuber stands. Each indicates daily rates c; between 0.4 and 0,75 inches per day. Established stands of Typha and Cyperus exhibit rates between 0,98 and 1.5 inches per day. This suggests that initial evapotranspiration rates will be lower than might be realized after the absorptive root zone is fully developed, Fu~ther support for this is given by Pratt (Personal Communication, 1985) who indicates that transpiration rates have increased annually in his Cattail ponds each of the three years since it was planted. These data were collected in areas of high humidity and would thus be expected to represent low values compared with potential rates in the G~and Junction region. On the basis of the botanical, environmental, and experimental considerations presented here, evapotranspiration rates equivalent to the low median value of 0,75 inches per day is judged to be a realistic expectation for a young stand in Colo~ado, over the period of its growth season, 2. Production Production, when coupled with an obligation to concentrate salts from within a saline water inflow, depends upon the adaptive capacity of a plant to function in saline environments, the way the environment is enginee~ed to take advantage of that capacity, the relationship between photosynthetic activity and the amount of solar radiation available, and the length of the growing season, Growing season, in turn, is a direct function of temperatu~e and the duration of the freeze-free period, a, Impact of Salinity Salinity is known to reduce yield in all plants; the questions however are 1) under what conditions and 2) to what extent, The very large majority of studies done have focused on answering the second question on the basis of single va~iable laboratory experiments. Parrondo, Gosselink and Hopkinson (1978), for example grew three salt marsh grasses (Spartina alterniflora, Spartina cynosuroides, and Distichlis spicata under controlled conditions, p~oviding only a graded scale of salt solutions (ranging from NaCI = 0 g/liter to 32 g/liter) as the rooting medium. Under their conditions. yields of all plants declined with increasing salinity, Effects were general, since root-shoot ratios remained fairly constant. This study. as well as similar studies by McMillan (1959) and Choudhuri (1968) on Typha, Rozema and Blom (1977) on A~rostis stolonifera and Juncus ~erardii, Haines and Dunn (1976) on Spartina alterniflora, and Falco and Cali on the germination of salt marsh plant seeds. led to the conclusion that yields will invariably decline as salt concentrations increase, Turner (1976) observerd that the productivity of salt marsh species unde~goes a north-south gradient that parallels total solar energy inputs at a .20 - .35% conversion efficiency, and 19,