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If the source of-salt is the Paradox Formation then it most likely is a natural feature of this valley.-.However, it should also be identified that the gas plant located in this-area has several ponds that may contain-brine waters. The potential for surface and/or subsurface leakage should be..examined in 'the future. The high salt concentrations in the entire northern portion of the study area precludes the use of ground water for the creation of fish ponds. However, water could be imported from. the Colorado River, from the strong Wingate Formation springs' that erupt at Matrimony Springs or the Old Ranch House Springs, or from Mill Creek via irrigation ditches: Ponds-could be created and filled with-these higher quality waters.- However,. because any-pond. sunken into these landscapes will be surrounded by brine waters, the potential for leakage .into the fish ponds is high.- We can therefore, not recommend-this as a viable land use. The interaction of flooding and salt accumulation in ground ..waters as well as soils must be discussed. We analyzed aerial.,. photographs of the study area from the years 1950, 1955, 1962, .1971, 1980, 1983 and .1991. Cottonwoods stands occurred in the area affected by-this salt plume in the 1950, 1955 and 1962 :photos. However,. by 1971 most of -the cottonwoods in this area are no longer visible, .indicating-that they died.. The hydrologic analysis presented earlier indicated that Colorado River flows. of 40,000 cfs and above are required for the river to flood into the study area.. The flood frequency analysis .presented in Table 2 indicates that overbank flooding of at least 5 days duration occurred every-1.86 years, approximately every ,.other year, during the period .1914 to 1958. However, from 1959 to 1982 no year had 5 or more-days with ,flows of 40,0.00 cfs or above. We hypothesize that-the reduction of flooding eliminated the salt flushing function of the Colorado River. Brine was no longer removed from soils or groundwater and salinity increased during the 1960's resulting in cottonwood death. This scenario also paved the way for massive invasion of the halophyte, salt cedar (Tamarix ramosissima). While researcher on western floodplains attributes vegetation change to hydrologic modification the changes documented are typically related to flood frequency, scouring, and lowered water tables (3ohnson 1991; Bradley and Smith 1982 and others). .Here the hydrologic changes have had the additional impact of allowing salts to accumulate which make the site unsuitable for non-halophytes.- 36