WATER RESOURCES OF ORANGE COUNTY 31
water for human consumption have already been discussed. Very little information is available on quality of water standards for livestock watering, but it is assumed that water safe for human consumption is safe for animals. In general, animals can tolerate higher mineralization than man.
The Department of Agriculture and Government chemical laboratories of Western Australia list the following limits for dissolved solids in ppm:
Poultry 2,860 Pigs 4,290 Horses 6,440 Cattle, dairy 7,150 Cattle, beef 10,000 Adult sheep 12,900
Investigators have found that water with a dissolved-solids content of more than 15,000 ppm is dangerous if used continuously for livestock watering. The water from the Floridan aquifer in eastern Orange County is the most highly mineralized. The water from a few wells exceeds 3,000 ppm in dissolved solids but none exceed 4,000 ppm.
The chemical quality of water is important in evaluating its usefulness for irrigation. The quality requirements for irrigation varies with the nature and composition of the soil and subsoil, topography, quantity of water used and method applied, climate, and type of crops grown. Good soil drainage is important where irrigation is practiced. Water of good quality for irrigation may not produce good crops on poorly drained land, whereas highly mineralized water may often be used successfully on open-textured well-drained soils.
There is much published material on the quality requirements of irrigation water for various crops grown under varying conditions. U. S. Department of Agriculture Circular 969 entitled, "Classification and Use of Irrigation Water" by L. V. Wilcox (1955), classifies irrigation water based on electrical conductivity in micromhos/centimeter. The dividing point between four classes is 250, 750, and 2,250 micromhos. Wilcox points out that ". . in classifying an irrigation water, it is assumed that the water will be used under average conditions with respect to soil texture, infiltration rate, drainage, quantity of water used, climate, and salt tolerance of the crop." All water in Orange County is suitable for irrigation. The artesian water in the eastern part is high in