Foam accumulating in the Shalva Stream near the southern Israeli city of Kiryat Gat turned out to be soap flowing into the river from a local factory.
When the foam was spotted, supervisors from Israel's Environmental Protection Ministry and Ashkelon's Municipal Organization for Environmental Quality began investigating the cause.
The investigation showed that the foam was hundreds of liters (dozens of gallons)of soap which had flowed into the river from the "Sabon Shel Pa'am" factory in Kiryat Gat.
According to the factory, the soap began leaking when a forklift damaged a container of soap.
The Environmental Protection Ministry opened an investigation into the incident, and will fine the factory for violating the sanitation laws.