Tens of millions of cubic meters of untreated sewage are flowing into Israel from the West Bank and East Jerusalem, polluting streams in Israel and the West Bank, according to a new study that for the first time provides quantitative measures of such wastewater.

The Environmental Protection Ministry recently formulated a cabinet resolution on preparing to deal with this ongoing pollution.

According to the resolution, within four months a government plan will be drawn up to deal with cross-border hazards, first and foremost the flow of some 60 million cubic meters of untreated sewage across the Green Line.

Implementing the plan will require a significant boost in manpower for both the Civil Administration and the environment ministry, and budgets of hundreds of millions of shekels for pipelines and purification installations. The new study was conducted by the Water Authority and the Israel Nature and Parks Authority.

The estimate of pollutants focused primarily on the large streams, at which flow meters were installed two years ago to measure the quantity of effluent passing through them. The data are for the years 2014 to 2016.

Every year, some 90 million cubic meters of sewage and wastewater is generated across the Green Line. Of this, 21 million cubic meters comes from the settlements, some of which have built purification plants. By contrast, most of the Palestinian villages and cities let their sewage flow into the environment untreated.

Nahal Kidron has the largest quantity of wastewater flowing through it, with 14 million cubic meters annually. Some of this effluent comes from Arab and Jewish neighborhoods in East Jerusalem that have not been hooked up to the wastewater treatment system that serves the western part of the city.

Nahal Hebron has a serious problem with industrial wastewater, which contains toxic metals like chrome; some 24 of the 28 measurements taken in the stream found chrome present. The wastewater of Nahal Hebron previously flowed untreated into the Green Line as well, but recently a purification facility went online and some of the treated wastewater is utilized for irrigation.

In terms of most polluted streams, Nahal Hebron is the worst. In addition to chrome, other pollutants include nitrogen and phosphorus, which kill fish and other wildlife. The high concentration of pollutants in the stream also poses a risk to the groundwater in the mountain aquifer, which supplies drinking water to the national water system.