Israel stands to lose large amounts of drinking water due to poor quality and problems associated with drought years, according to the Water Authority. Among the threats to water quality, cowsheds in the south have been found to cause groundwater pollution, and sewage could soon pollute drilled wells in the Western Galilee.

The Water Authority official in charge of quality, Sarah Elhanani, last week presented statistics at an emergency conference on water at the Agriculture Ministry's Beit Dagan facility: It emerged that the coastal aquifer, one of the two largest in the country, is fast becoming saline. Seventy years ago the quality of the water drawn from 80 percent of the area of the aquifer was defined as good; today, only 40 percent is so defined.

Elhanani said that a recent joint study by the Beit Dagan Veterinary Institute and researchers at Ben-Gurion University of the Negev showed that cowsheds in the southern communities of Be'er Tuvia, Masuot Yitzhak and Orot are the source of increased concentrations of salt and manure in groundwater and nearby top soil. Smaller amounts of veterinary hormones such as testosterone and estrogen were also detected.

Nine wells used for drinking water have been closed in the industrial zones of Holon, Rishon Letzion and Bat Yam in recent years due to industrial pollution, including high levels of chromium. Concentrations of perchlorate used by the military industries were found in 11 wells in Ramat Hasharon and Tel Aviv, leading to their closure, and the material continues to spread.

A study on the impact of sewage on wells in streambeds by researchers led by Anat Magal of the Geological Survey of Israel was commissioned by the Water Authority following the severe case of sewage pollution two years ago of drinking water in wells drilled at the Kabri springs and Ein Ziv in Western Galilee. The study was published last week. Researchers introduced water containing dye at sites where sewage was suspected of percolating into wells, and the marked water took only 80 to 100 hours to cross 14 kilometers and reach the drill sites.

The test indicated that large areas of the region could find themselves without a water supply within days of a sewage pollution event.

In addition to improving treatment and delivery systems, the Water Authority has recommended the installation of water-quality monitoring systems to quickly detect sewage pollution.