Monitoring the river to locate sites where mosquitoes incubate is one of the Yarqon River Authority’s routine operations carried out annually from the end of the rainy season until the rains return after the long hot summer. Public sensitivity to such pests coupled with fear of West Nile Fever make efficient monitoring and eradication an absolute necessity, and these are applied in accordance with the strictest monitoring practices. The monitoring results seen in recent years clearly indicate a significant reduction in the incubation of mosquito larvae in the Yarqon River, especially in the section downstream from the point where effluents from Ramat HaSharon enter the river as far as the “Seven Mills” site. The reason for this development is the improvement in water quality and the consequent appearance of a population of predators such as fish and additional aquatic creatures.
The performance of the eradication work depends on the monitoring results and it is not conducted systematically at intervals of 10 days as was the case in the past. BTI (a biological pesticide – bacteria which affect only the mosquito larvae) is the principal pesticide used in this eradication process and when the need arises MLO oil is also used (this is a mineral oil which kills the mosquito larvae but also damages aquatic creatures that breathe atmospheric oxygen)
The river is monitored and the mosquitoes eradicated in five separate sections
In the upper section of the Yarqon River between Neve Yarak and Abu Rabah: Over the years no larvae eradication was needed in this section owing to the population of predators present in the water. However, a shortage of fresh water caused extensive areas to dry up and consequently the predator population disappeared and mosquito larvae began to develop. Recently an allocation of fresh water was approved and the need for further eradication is expected to decline, and possibly cease altogether.
From the Qana River to the point where effluents from Ramat HaSharon enter the river: The South Sharon Regional Association for sanitation conducts the eradication program based on the monitoring results and as instructed by the Yarqon River Authority.
From the point where effluents from Ramat HaSharon enter the river to the Geha highway: The Yarqon River Authority carries out the mosquito eradication program in line with the monitoring indicators.
From the Geha highway to the Ten Mills: The Yarqon River Authority carries out the mosquito eradication program based on the monitoring indicators.
From the Ten Mills to the Seven Mills: The Yarqon River Authority carries out the mosquito eradication program in accordance with the monitoring indicators.
Mosquito fish (gambusia affinis), which prefer mosquito larvae as food, reproduce naturally in the river in various places in its middle section during the spring months. From June to August the mosquito fish may be found upstream in the river as far as the Geha highway area. A population of St. Peter’s fish (tilapia) has been found in the river as far as the point where effluents from Ramat HaSharon enter the river.
The improvement in the water quality was discerned in the Yarqon River after the new wastewater treatment plant for Ramat HaSharon came into operation and the use of herbicides on the vegetation growing along the river banks close to the water’s edge was stopped for the third year running. These steps facilitated the partial rehabilitation of the ecosystem and the development of habitats for the population of aquatic insects, which also reduce the number of mosquito larvae in these sections of the river.