119—Clear Lake clay, moderately wet. This very deep soil is in alluvial basins. It has been artificially drained. Slope ranges from 0 to 2 percent. Elevation ranges from 20 to 100 feet. The mean annual precipitation is about 25 inches, and the mean annual air temperature is about 58° F. The frost-free season ranges from 245 to 275 days.
Typically, the surface layer is dark gray, neutral and mildly alkaline clay about 44 inches thick. The underlying material to a depth of 62 inches is grayish brown, moderately alkaline clay.
Included with this soil in mapping are areas of Conejo loam, a soil that is similar to this Clear Lake soil but has a water table at a depth of 20 to 36 inches, and soils that are similar but have a dark grayish brown surface layer. Also included, in the vicinity of the Pajaro Dunes and Shell Road, is about 60 acres of a soil that is poorly drained.
Permeability of this Clear Lake soil is slow. Available water capacity is about 7.0 to 9.5 inches. Effective rooting depth generally is 60 inches. For water-sensitive plants, however, the rooting depth is limited by the depth to the water table. The water table is at a depth of 36 to 72 inches. The water table has been lowered and maintained at this depth by pumping and by use of tile drains and diversion ditches. Runoff is very slow, and the hazard of erosion is slight.
This soil is used mainly for irrigated row crops. Crops commonly grown are Brussels sprouts, strawberries, broccoli, and cauliflower. A few areas are used for irrigated pasture and as homesites.
Irrigation of this soil at a slow rate but for longer periods of time reduces the ponding of water on the surface. Tillage or field traffic when this soil is wet can cause extensive damage to its structure. The addition of organic matter improves the tilth and increases water in filtration.
If this soil is used for pasture, grazing should be restricted to times when the soil is not wet. Grazing when this soil is wet causes surface compaction, which results in poor aeration.
This soil is severely limited for community development by its high shrink-swell potential and low strength. This necessitates special design of dwellings, local roads, and streets. Slow permeability and the high water table increase the possibility of failure of septic tank filter fields. Surface drainage is needed if the soil is used as building sites. Capability units 2w-5 (14), irrigated, and 3w-5 (14), nonirrigated; Storie index 43.