WATER RESOURCES OF ORANGE COUNTY 141
No survey of individually-supplied domestic water use in Orange County was made because of the time that would be involved and the fact that very few of these wells have meters or any means of determining how much water is used. Individual water use was determined by multiplying the population so supplied (66,000) by the per capita domestic use of 100 gallons per person per day as determined in areas supplied by public water systems. Total individual domestic use in Orange County is estimated to be about 6.6 mgd.
Treatment of ground water for public use consists of chlorination for sterilization or chlorination plus aeration to remove hydrogen sulfide gas from the water.
Agricultural use of ground water in Orange County in 1963 was estimated to be about 5.5 mgd. Most of the agricultural use of ground water is for the irrigation of some of the 63,000 acres of citrus in the county. The use of ground water for irrigation of citrus is increasing rapidly and this trend is expected to continue. Recent studies by the Citrus Research Institute at Lake Alfred have shown that iririgation can increase citrus yield by 25 percent or more, and the percentage of groves that are irrigated is increasing. Most lakes that are practical sources of irrigation water are in use; therefore, most new irrigation supplies must be obtained from wells. Some groves that were formerly irrigated from lakes are now irrigated from wells because residents on the lakes objected to water being withdrawn from the lakes during droughts when the lake levels were already low.
Another factor tending to shift irrigational use from lake water to well water is the increasing use of permanent overhead sprinkler-type irrigation systems as opposed to portable perforated pipe systems. In general, there is less clogging of the sprinkler heads from well water than from lake water unless the lake is exceptionally clean.
Permanent sprinkler systems are more expensive to install than portable systems; however, the lower cost of operation (mostly labor) usually makes the permanent-type systems less expensive in the long run. Another advantage of permanent-type systems is that the water can be applied when it is needed, whereas labor for portable irrigation systems is not always available when it is needed most. Because permanent irrigation systems are relatively simple and inexpensive to operate once they are installed, they are used more frequently. This will probably increase the quantity of water used for irrigation.