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~'. ~. The salinity measurements made on these 13 sites over the past ten years have not shown any significant increase in soil salinity over time. It has confirmed that irrigation water applied .in excess of crop water needs will keep salts flushed from the plant root zone. These salts ultimately end up in the Colorado River. continued soil salinity monitoring efforts may not prove anything. ;:~;r{ " , f. Irrigation Adequacies At sites: Data from monitored fields indicate that overuse of water is prevalent because of the abundant supply of inexpensive irrigation water. A wet spring in May delayed irrigation by about a month in 1993. More than 50\ of the farmers monitored in 1993 practiced a high degree of good irrigation water management. A few farmers are concerned about paying Qverage cost for excess irrigation water. Most operators under the M&E program, received individual irrigation summaries at least once during the irrigation season.. Data obtained from their sites was explained to them, and recommendations were provided to improve irrigation'effici~ncies, e.g., better irrigation SCheduling, adjustment of set times or inflow rates, reducing or increasing time of set, and furrow flow or number of furrows. Before the start of the new irrigation season, some operators received soil moisture deficit data to help them with their irrigation management decisions. Very few operators made any changes to their existing irrigation practices. I .....-::.;.: Most sites were more than adequately irrigated. However; even sites with high deep percolation (16, 30, 53, and 54) tend to be under-irrigated one or more times during the 'season. sites 60, 51 and 56 were under-irrigated throughout the. irrigation season. However, field moisture testing at site 26 indicated adequate moisture during the time M&E data showed a deficit. This .site has hIgh water table and does not need to be irrigated! as. much. Site . . 56 may have been. under-irrigated, or ETa could have been overestimated. The producer said that his orchard yield was excellent and did not feel that he had under-irrigated the site. sites with low deep percolation, about 15\ to 25% of ETa, e.g. 13, 21, 26, 47, 58, 55, 56, and 61 tend to be under-irrigated during the third through fifth irrigation events (refer to individual irrigation data in Appendix D). Sites 33 and 36 with sprinkler irrigation systems were under-irrigated most of the season. .. g~ Infiltration Estimates: , , Application infiltration rates for each site was determined from individual site summary data provided in AppendIx D. At a. site, for each irrigation, the infiltrated depth was divided by the number of hours per set to determine an application infiltration ",.' ...... ..~:~~_:., 26