1. The next black waters which you observed were the works of the Amorites, their incantations, their wickedness, and pollution.
2. Israel was then polluted by sins in the days of the judgments, even though God showed many wonders to them.
Israel had been easily polluted by the Egyptian false gods while in Egypt, and by every group of people encountered in the wilderness journeys. When in Israel, they soon fell into the pollution of the idol worship of that land.
The Amorites are mentioned here as the source of Israel's pollution in the Promised land. Why are they mentioned? This was a particular group, which Israel had been ordered to exterminate when in the Promised land, and had they done so, they could not have been polluted by their wickedness.
"But thou shalt utterly destroy them... Hittites, Amorites, Canaanites, Perizzites, Hivites, and Jebusites, as the Lord thy God hath commanded thee. That they teach you not to do after their abominations which they have done unto their gods; so should ye sin against the Lord your God."
The Amorites dwelt in the mountains, the Jebusites dwelt in Jerusalem, the Amalekites dwelt in the south, and the Canaanites dwelt on the sea coast and in the Jordan valley.
Syria and Palestine were called by the Babylonians to be the "land of the Amorites".
A hint more of why the Amorites are singled out here as the source of defilement is found in the Bible:
Og was an Amorite (Deuteronomy 3:8), and he is described as the last of the Rephaim (giants). In Deuteronomy 3:11 we are told that his bedstead was made of iron, and was 9 cubits long, and 4 cubits wide (that is - 13 and a half feet, by 6 feet). Og, king of Bashan, and Sihon king of the Amorites were both slain before the entrance into the promised land with Moses still being God's chosen leader for the people (Numbers 21:33-35, Deuteronomy 3:1-12). Many Amorites (part angel and part human giants) still existed in the land. Their seed could have corrupted the lineage through which Christ would come. The Israelites were commanded to kill them.
"...a fire shall come forth out of Hesbon, and a flame out of the midst of Sihon and shall devour the corner of Moab."
"...slew the mighty kings, Sihon, king of the Amorites, and Og, king of Bashan."
"Sihon, king of the Amorites... Og, king of Basham."
THE SINS THAT POLLUTED THE CHILDREN OF ISRAEL INCLUDE:
[1.] Wrong desires
(Some today desire to escape their problems and guilt by alcohol and drugs, and some seek sexual escapades, and some desire carnal wealth over spiritual wealth.)
[2.] Spiritual idolatry
(They worshipped the golden calf, and some today worship power, position, money, or recreation.)
(When Moses read the commandments to the people for the first time, they answered: "We can do it" but they proved quickly they could not. Today many likewise prove unfaithful to the Lord.)
[4.] Opposed God's leadership
(They complained, rebelled, and strayed from God's ways and directions. Even the manna was complained about. Notice most, if not all churches today, and listen to the complaints.)
(Easily they grew bored and restless and even said to God "Would to God we would die in this wilderness." God granted their request. Today the murmuring is listened to by God, and some may get what they request.)