Damage from pollution has been evident in the Yarqon River since the end of the 1950s. Up until that time 25,000 m3 of spring water flowed from the springs at the Yarqon’s source into the river every hour. Since the end of the 1950s the pumping of the springs’ waters to provide drinking water started and from that time onwards the volume of spring water reaching the Yarqon has decreased constantly. (In 2004 following a government decision, 200 m3 of water per hour from the local aquifer flow into the river, in keeping with the allocation by the Water Commissioners and this quantity is less than 1% of the original flow emanating from the springs. This discharge has increased to 600 m3 per hour, improving the ecological conditions in the upper section and the river’s capacity for self-purification).
The damage done to the river deteriorated further as the cities surrounding it developed and the common cesspits were gradually replaced by a central sewage system. Urbanization processes in the past resulted in the flow of industrial wastewater, raw domestic wastewater, and low quality effluents in the river. At the beginning of the 1960s and in the 1970s several wastewater treatment plants were constructed to alleviate that plight, but the effluents produced were of inferior quality and the pollution of the Yarqon channel continued unabated.
The intensification of the urbanization process coupled with the decline in the river’s self-purification capability resulted in an increase of the relative importance of the rainfall runoff water.
Together with the runoff water many pollutants enter the river and sink to the riverbed or remain dissolved in the water. These pollutants include oils and fuel, pesticides, heavy metals, sediment and many kinds of garbage. The pollutants reach the Yarqon River with the first rains of the year when little or no water flows along the river and therefore, as already noted their negative effect is very serious.
Specific pollution sources included:
- The Kfar Saba/Hod HaSharon WWTP: The plant produced effluents of secondary quality which are unsuitable for input into the Yarqon’s flow and therefore cannot contribute to its rehabilitation. As a result of the Ministry of Environmental Protection’s demand, the treatment process now includes tertiary treatment at the quality defined by the Inbar committee, an inter-ministerial committee, and the effluents are suitable for discharge into the Yarqon.
- Ramat HaSharon WWTP: The plant produced effluents close to tertiary quality which may be used to some extent for the river’s rehabilitation, and this is according to the initial tests which indicate an improvement downstream from the point where the effluents are added to the flow. Today the quality attained meets the Inbar committee requirements.
- South Sharon regional council WWTP (formerly known as the Nir Eliyahu WWTP): Wastewater from Qalqilya, Alfei Menashe, and Kibbutz Nir Eliyahu are treated at this WWTP and future plans will also enable it to treat the wastewater from the towns and villages along the Qana River. The frequent spills from the WWTP pollute the river due to their poor quality, and sometimes faults or damage to the wastewater collection system cause more serious pollution.
- The Ayalon River: The Ayalon River pollutes the Yarqon River whenever the flow rate in the Ayalon exceeds the pumping capacity of the installations operated by the Dan Regional Association for Environmental Infrastructure. The Association has been maintaining an earth weir on the Ayalon River for many years in the vicinity of the Ezra neighborhood in South Tel Aviv. The water pumped out is mainly effluents from the Nesher reservoir, which collects the effluents from the Ramla/Lod region.
Pollution from non-point sources: These include pollution originating in agricultural lands and urban areas which flows into the Yarqon River when it rains. The surface runoff water contains pesticides, fertilizers, oils and fuel, sediment, detergents and many bacteria. It should be borne in mind that large concentrations of these pollutants enter the river in concentrated form especially during the first rains of the year. Combating these unspecified pollutants is achieved mainly by preventing them from reaching the drainage systems and this action calls for the proper farm management of agricultural lands, covering over areas where pollutants are treated as well as the separation of the pollutants from runoff water.