the continuous availability of groundwater to riparian phreatophytic vegetation such as saltcedar tamarix, sp. and cottonwood populus, results in large transpiration losses to the atmosphere, particularly in summer, when high transpiration rates usually coincide with peak consumer demands for ground- and streamwater. removal of this vegetation can cause ecological imbalances and be environmentally and aesthetically unacceptable. spraying a nontoxic antitranspirant (at) on phreatophyte foliage, on the other hand, may reduce transpiration losses and also preserve the vegetation. this research project therefore investigates: (1) the magnitude of water lost through transpiration by phreatophytes using gravimetric, lysimetric and energy budget techniques; (2) plant and environmental factors which influence the water relations of the vegetation, using porometer, pressure chamber, and gas-exchange measurements; (3) selection of suitable at materials by laboratory and greenhouse screening tests; (4) field testing of ats, sprayed from the ground and by air, for transpiration reduction; and (5) at effects on terrestrial and aquatic wildlife of riparian habitats using acute toxicity and other experiments