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The Pathology of a Polluted River
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The Yarkon River had not always been contaminated. Until the 1950s, a re-mote risk of bilharzia (schistosomiasis) was still the only “environmental” concern for the children who swam and fished its rushing waters.[24] The river's 28-kilometer run to the Mediterranean at Tel Aviv's northern border still resembled this description from an 1891 travel guide: “The Yarkon River leaves from the base of a small hill called Ras El Ayin. Many other springs and rivers flow into it until it becomes a roaring river that zig zags until falling to the sea. This is one of the largest rivers in the land, and its power turns mills, and small fish can be caught in it.”[25] Biologists would later discover that the river boasts a species of small fish, lavnun ha-Yarkon, that exists nowhere else in the world. Even today, a rich variety of native plants remain along the banks. When the little nutria (a furry rodent) was brought to Israel in an unsuccessful fur enterprise near the river, the animals soon escaped and took to the warm climate, joining the local fauna.

Historically, the Yarkon also enjoys a rich and varied history. The strong flow and the thick wetland vegetation surrounding it created a sub-stantial land barrier. This gave the river considerable military importance. Whoever controlled the narrow land passage between Migdal Zedek and the Fort of Antipater dominated the surrounding area and a major north-south route. Over the past millennia, a series of military contests ensued around the river's narrow headwaters, as so often is the case for such strategic locations.[26]

But the Rosh ha-Ayin springs were tapped in 1956, and most of the Yarkon's natural 220 million cubic meters of annual flow (220 billion liters) was diverted to the south of Israel as part of a national irrigation program. The river quickly lost its vitality.[27] Were it not for the allocations to up-stream farmers, the river would have become completely moribund. The untreated

sewage of the many municipalities that make up the Central Israeli Dan and Sharon region replaced the clean natural spring waters bubbling out of the Mountain Aquifer. These wastes were augmented by chemicals and detergents from factories in the many industrial zones that lay along the flood plain, discharges from the many solid waste dumps in the water-shed, and runoff, carrying residues of oils, from roads and industrial debris.[28]

It took little time for Israelis to grow used to the new stench-filled and stagnant reality. It was just another annoyance of daily life. A line in the popular song “Only in Israel” from the 1960s summed up what was al-ready the common perception about the perennially polluted river: Ha-Yarkon tamid yarok, “The Yarkon is always green.”[29]

In fact, the river is not uniform, breaking into three separate sections:

  • The upper Yarkon, which has been returned to a fairly clean state
  • The central (and largest section), which receives municipal waste-water and effluents at various levels of treatment
  • The lower four kilometers, where seawater flows in to fill the vac-uum and tidal fluctuations ensure regular replacement of the saline estuary

Even if authorities had been interested in addressing the water quality of the Yarkon, its complex pollution profile makes it a particularly chal-lenging resource. The river's watershed contains some eighteen hundred square kilometers stretching from cities in northern Samaria, such as Nablus, to the sea. Controlling for all the runoff that eventually reaches the Yarkon is a daunting task, today requiring international cooperation.

Raw sewage coming from the Kaneh River in the West Bank, for in-stance, reaches the stream with a biological oxygen demand (BOD) reading of 250 milligrams per liter. The Israeli standard for this parameter, which measures the amount of organic waste that steals oxygen from aquatic sys-tems, is 20.[30] The Yarkon River master plan, based on the river's sensitiv-ity, recommends that entering sewage be treated to a BOD level of 10, or 25 times lower than the concentrations that actually reach the river.[31] The Kaneh is just one example of many pollution sources. In addition, the Ayalon, Shiloh, and Hadarim tributaries carry their own sewage loadings.

The range of pollutants is also enormous. The small factories and sewage discharges whose effluents indirectly reach the tributaries make up only the urban part of the pollution portfolio. Farmers near the banks contribute a range of agricultural pollutants, including pesticides and animal wastes, through diffused (nonpoint) runoff, which may have been responsible for the P. boydii that harmed and killed the athletes.[32] In the most densely populated

area of the country, where land prices are highest, there simply is not much land available to install the biological processes required for treatment.

Once the heart of the river became polluted, it lost its biological integrity and the ecological law of “unintended consequences” set in. Pest control of-fers one example. Since the British brought the Gambusia fish (Gambusia affinis) to Palestine in 1924 as a remedy for the malaria problem, these fish have been employed for mosquito control,[33] but the central Yarkon pollutants are too virulent even for these hardy mosquito eaters. Without fish in the wa-ters, mosquito populations are not curbed by a natural predator and quickly became an urban nuisance. This is particularly aggravating for Tel Aviv resi-dents, who like to leave their windows open and frequently do not have screens.

The light spraying of MLO, a thin sheen of oil on the surface, was selected as the “lesser evil” of the available control options.[34] Even if it affects only the mosquito population (a dubious assertion to be sure), it is not always possible to apply the MLO from a boat, so access roads along the river are required. This in turn disturbs vegetation that is supposed to grow back as part of recla-mation efforts. The exposed land hastens erosion, silting, and turbidity. Treating the symptoms rather than the causes of a sick river has limitations.

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The Pathology of a Polluted River
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