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The unconsolidated contental deposits consists chiefly of alluvium but in some areas include widespread lacustrine and marsh or estuarine sediments. These deposits constitute late Cenozoic fill in the structural trough, whose axis in the San Joaquin Valley lies west of the present topographic axis of the valley. Appreciable folding and minor faulting also has occurred; however, these structural features have had no significant barrier effect on ground-water movement. Consolidated rocks form the boundaries beneath and on the flanks of the productive ground-water reservoir in the unconsolidated deposits. Only minor quantities of water occur in joints or fractures in the consolidated rocks in the Sierra Nevada, and the principal water supply to the valley-the stream runoff- passes over them. Ground water occurs under both confined (artesian) and unconfined (water table) conditions in the Central Valley. The degree of confinement varies widely because of the heterogeneity of the continental deposits. In the big alluvial fans on the east side of the San Joaquin Valley, the ground water is unconfined. The most extensive confined aquifer is the major aquifer system overlain by the Corcoran Clay Member of the Tulare Formation, which covers more than 5,000 square miles in the San Joaquin Valley. Recharge to the ground-water reservoir is by infiltration of rainfall, infiltration from streams,canals,and ditches,by infiltration of excess irrigation water,and by underflow entering the valley from tributary stream canyons. 3.3 Historical Use Aerial photographs were reviewed for evidence of prior on-site and off-site Information features that could pose a potential environmental concern to the subject property. These features included, but were not limited to, sumps, pits,ponds, `— ASTs, landfills, outside storage of hazardous materials, and general land use. Aerial photographs from the years 1968, 1981, and 1992 were reviewed at Pacific Aerial Survey, Oakland, California. The earliest available photograph covering the property, dates to 1968. The following observations were made during the aerial photograph review: �- 5/1/1968: (1:30000) The Tiki Lagun is visible on the photo however it is a smaller operation with some open boat docks and one covered boat dock. The campground area to the east of West McDonald Road r was not visible. The surrounding areas appear to be in agricultural use. An agricultural processing operation appears about one mile to the west of the subject property across Turner Cut. 10118/81: (1:54000) The subject property has been expanded since the previous photograph. All of the covered boat docks are visible,and there are some campground spaces on the north of the property, east of West McDonald Road. The surrounding area is still predominantly agriculture. BLASLAND,BOUCK&LEE.INC. NEWT1q.WPL) 5/706 engineers & scientists 3-4