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This is the first of two articles offering different views on who wins and loses in water trades. The first, by Mike Rosen, analyzes possible effects of three policies by winch irrigation districts might distribute water transfer gains. The second, by Rodney Smith, reinterprets the Rosen data and defends a “negotiated certificates” water trading scheme. FA. The Imperial Irrigation District and the Metropolitan Water District (MWD) of Southern California have recently concluded an agreement which is historic because of its long-term nature and the volume of water to be transferred. Imperial will transfer 106, 110 acre-feet of water to MWD annually for 35 years in exchange for MWD providing funds for Imperial conservation projects. The projects are to be completed by 1994 and paid for by MWD over a 35-year period for a total cost of $222 million. The effective price of water to Metropolitan will be about $100 per acre-foot per year. Proposals for alternative uses for these funds could become a major source of conflict within the Imperial district. Three potential policies are examined in this article. At present, Imperial receives and controls the funds, but the district is contemplating ways to allow district landowners and farm operators to receive funds directly. Water transfers have been promoted as voluntary transactions in which there can be no losers. But decision-making within water districts is collective in nature, and intra-district conflict may arise. Individual members of districts may have reason to oppose transfers, and aggregate benefits may not be realized.

Provided that their districts pursue water transfer opportunities in good faith, landowners benefit from district control of water transfers. Rosen's case study suggests that the value of district control may be substantial. But contrary to Rosen's assertion, tenant farmers need not fear economic loss from water transfers.

The parasite Trioxys brevicornis was imported from Czechoslovakia and released in California to help control the European asparagus aphid. Field performance of this parasitic wasp indicates it has potential to become permanently established in California. Aphid parasitism by T. brevicornis was especially good in comparison.

To increase irrigation uniformity and to reduce drainage volumes, some San Joaquin Valley growers drag weighted steel cylinders (torpedoes) in furrows before irrigation to speed the advance of water across the field. The effectiveness of this practice and the reasons it works have been investigated. At one site, torpedoing reduced the furrow's steady-state water infiltration rate. A similar phenomenon was not observed at the other two sites investigated. An increase in the irrigation advance rate of torpedoed furrows, ranging from 15 to 30%, was noted at each site evaluated. Torpedoed, nonwheel furrows had water advance characteristics similar to wheel furrows. Torpedoing nonwheel furrows therefore resulted in more equal water advance rates among furrows.

Only one-fifth of the drainage-impacted lands in the San Joaquin Valley's west side discharge their irrigation return flows into the San Joaquin River. One option for the remaining lands is to dispose of drainage waters in evaporation ponds. Eventually, the evaporite salts that form in these ponds must also be removed. In some cases, these evaporites could constitute hazardous wastes.

Three devices that physically treat irrigation water were tested in the laboratory and the field. Results of these experiments indicate these water conditioners were ineffective in increasing the infiltration rate of water into the soil or in preventing calcium carbonate precipitates from clogging drip emitters under the conditions in which they were tested.

Poor water penetration constitutes a major production constraint for more than 400, 000 acres of agricultural land in California. The associated economic losses are particularly appreciable in the production of fruit and nut crops. In response to a hypothesis that cover crops may improve water infiltration in orchards, studies were conducted at Davis and Ceres. After 3 years' study, results indicate major benefits are possible with the planting of cover crops.

Botryosphaeria panicle and shoot blight of pistachio caused by the fungus Botryosphaeria dothidea is favored by high temperatures, 80° to 85° F, and wetness periods longer than 12 hours. Based on these requirements, the disease becomes severe in late spring and summer when temperatures increase and after sprinkler irrigations begin. The disease was substantially reduced by shortening sprinkler irrigations from 24 to 12 hours and from 48 to 24 hours in two commercial pistachio orchards in the Sacramento and San Joaquin valleys, respectively.