The Kidron River runs from Jerusalem through the Judean desert and into the Dead Sea. For thousands of years, the river has brought life to the Kidron valley and supported human settlement in the area. The river is fed by the Gihon Spring, Jerusalem’s natural water source which was diverted in ancient times to bring water into the city. Like most rivers in the area, the Kidron runs dry for much of the year and is susceptible to flash flooding during heavy rains.
The Kidron runs through the valley between the Old City of Jerusalem and the Mount of Olives, passing just below the eastern retaining wall that supports the Temple Mount. A mishnah on our daf reports that it played a role in carrying away wastewater from the Temple:
These remainders of blood from the outer altar and those remainders of blood from the inner altar are mixed in the canal beneath the altar and flow out with the water used to rinse the area to the Kidron River.
You might think the addition of blood from sacrifices would taint the water and cause people to avoid it. However, the mishnah suggests otherwise:
This water was sold to gardeners for use as fertilizer.
Lest you think that the farmers were misappropriating blood which had been sanctified for use in the Temple, the mishnah tells us that:
The gardeners paid for this water and thereby redeemed it from its sanctity.
In recent times, as the population of Jerusalem and the surrounding areas has grown exponentially, the debris and sewage that flow into the Kidron River makes it one of the most polluted streams in Israel. Unlike the blood from the Temple, which seems to have added to the value of the water, the modern day runoff is wreaking havoc on agriculture and the local ecosystem, endangering humans and wildlife.
The blood that drained into the Kidron River in ancient times was a part of the sacrificial system whose purpose was to purify from sin. Today, the waters of the Kidron need their own purification in order to support life in the river’s watershed. Efforts to improve the ecosystem are underway as part of the Kidron River Restoration Project.
Because the river runs through areas controlled by both Israel and the Palestinian Authority, the complexities of this project rival the most complex of talmudic arguments. Just as the rabbis framed their debates as ones that were formulated for a higher purpose (l’shem shamayim), let’s hope that the goal of restoring the environment and providing clean water to its inhabitants will be the higher purpose that leads to the purification of the waters of the Kidron.
Read all of Yoma 58 on Sefaria.