Quotation for Sanhedrin 10:17

The waters of the Karmiyon and the waters of Pugah are unfit, because they are marsh waters. The waters of the Jordan and the waters of the Yarmuk are unfit, because they are mixed waters. And the following are mixed waters: a fit kind and an unfit kind that were mixed together. If two kinds that are fit were mixed together both remain fit: Rabbi Judah says that they are unfit.