One of Israel's three sources for fresh water, the coastal aquifer, is in danger of becoming unusable because of contamination, according to data collected by the Water Authority and the Health Ministry.

The data shows that over the past decade, 160 wells were shut down (because of various kinds of contamination) from an overall figure of 1,000 wells, which provide about 20 percent of the country's annual water consumption.

The main sources of contamination are: untreated sewage, salination stemming from the penetration of sea water, agricultural fertilizers and industrial pollutants, including heavy metals and carcinogenic organic products.

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Most of the sources of industrial pollution are no longer active, but the
materials spilled at those sites continue to contaminate the ground and seep into the aquifer.

"There are materials that can reach the groundwater in a matter of hours, and other types can take decades to get there," explained Prof. Daniel Ronen of the Water Authority.

In recent years, it has been found that gas stations are also a significant source for contamination of the groundwater.

"Only recently we discovered a layer of gasoline, near a gas station in the Tel Aviv area, that was four meters deep in the ground water," said Baruch Weber, district director at the Tel Aviv office of the Environment Ministry.

In recent months the problem of contamination of the fresh water sources has been discussed in ministries, and countermeasures are being considered.

All relevant authorities realize that due to a deterioration in quality, the amount of potable water that will be available from wells along the aquifer will be gradually decrease in the coming years.

Some of the contamination problems were discussed yesterday at a seminar
organized by the Environment Ministry's Tel Aviv office with the participation of representatives from the Water Authority and the Health Ministry.

The extent of the danger is reflected in the Health Ministry data on the Tel Aviv district, which shows that since 1980, some 88 drilled wells used for potable water were closed and that is more than half the available wells in the district.

Pressure on water carrier
As a result of the closures, the dependence on water drawn from the
National Water Carrier has risen significantly.

In many of the wells still in use, the process of contamination continues, even if the level as yet is still below the acceptable contamination standard for drinking water in Israel. For example, in 18 active wells, scientists found arsenic (an extremely toxic material) in samples tested. In nine wells, heavy metals such as lead and chrome were found in test samples.

Some of the experts raised the possibility that drawing potable water from the coastal aquifer cease; this proposal, however, was rejected by most relevant authorities.

"I think that it is still possible to rescue the aquifer, but this will have to be an effort that includes all parties in the system, and I hope that this is not too much for the State of Israel to manage," Dr. Yeshayahu Bar-Or, the chief scientist at the Environment Ministry said yesterday.

One of the ways that the contamination problem could be countered is through the installation of purification equipment in each of the wells showing high levels of pollutants. This was adopted in contaminated wells in Rishon Letzion and Ramat Hasharon.

Another option is to set up a number of large purification installations to which water drawn from various locations along the coastal aquifer will be piped for treatment.

At the Water Authority preparations are underway to set up a backup water
supply system for communities in which their wells were closed due to
contamination.

One such community, Bnei Dror in the Sharon region, has been without a local drinking-water supply as a result of contamination levels that exceeded the standard.

Professor Ronen also raised the problem of underground toxic gases that affect the water supply, even though it is not always easy to trace them.

This sort of contamination was discovered five years ago in the Israel
Military Industries compound on the municipal boundary between Tel Aviv and Givatayim.