The Los Osos Valley groundwater basin is located on the coast of central California. It extends about 3 miles inland and an unknown distance offshore, where it is in hydraulic connection with the Pacific Ocean. Its maximum onshore depth is about 1,000 feet. Groundwater flow in the basin was investigated using existing data, geologic mapping, drilling, and measurements of potentiometric head, water quality, and streamflow. The basin is underlain largely by relatively impermeable rocks of the Franciscan Complex. Basin fill consists of unconsolidated, complexly layered sediments of Miocene age or younger. Individual beds are generally thin and discontinuous. A three-dimensional digital model of the basin was developed and calibrated to match potentiometric heads and headdependent flows during water years 1970-77 and 1986. The model simulated poorly the steep vertical potentiometric heads, and it could not simulate perched water tables. In other respects, model results were good and not highly sensitive to likely errors in input data. Infiltrated rainfall contributes about 80 percent of annual recharge to the groundwater basin, and groundwater inflow accounts for almost all the remainder. Net recharge from Los Osos Creek is small. In water year 1986, outflow from the basin consisted of net municipal pumpage (24 percent), net agricultural pumpage (25 percent), net outflow across the ocean boundary (26 percent), perched-water runoff (16 percent), and phreatophyte transpiration (9 percent). During water years 1970-77 net municipal pumpage and net agricultural pumpage accounted for only 10 and 22 percent of total outflow, respectively. The population of Los Osos Valley is expected to increase by about 20,000 people by the year 2010, and municipal water use is expected to increase by about 1,700 acre-feet per year. The model was used to simulate the effects of various future water-supply and wastewater-disposal alternatives on the groundwater system. Results indicated that if wastewater is centrally treated and recharged to the groundwater basin, the entire projected municipal water demand can be met with locally pumped ground water without inducing seawater intrusion, even during droughts lasting 1 to 3 years. If wastewater is exported from the basin, however, large amounts of seawater intrusion are likely to occur even if nearly half of the municipal water demand is met with imported water. Consulting geologist registered with State of California.
The Three Kids manganese district, in Clark County, Nev., has produced between 15,000 and 20,000 tons of ore, which contained between 30 and 40 percent manganese, 1.5 percent iron, and 12 percent silica. It is estimated that the reserves in the district aggregate about 5,500,000 tons of.ore averaging about 10 percent manganese. Of this amount about 800,000 tons contains more than 20 percent manganese and 4,700,000 tons contains from 5 to 20 percent manganese. The manganese ore is a sedimentary deposit and consists of wad interbedded with lake or playa sediments belonging to the Muddy Creek formation of Pliocene (?) age. Where the manganese content is as high as 30 percent, the wad forms thick massive beds separated by thin almost barren partings. Where the content is low, the wad forms very thin lenses or small irregulaT blebs scattered through sandstone, or a cement for the sand grains. The zone of manganiferous beds ranges from about 10 to 75 feet in aggregate thickness, but at most places the thickness is between 25 and 40 feet.
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