Why? (1) Most meteorites are not stable in water. The metal will have rusted and the stone will have broken apart. (2) A meteorite in a stream bed would have had hits fusion crust worn off by abrasion against other rocks. There would be no way to identify it as a meteorite unless rusty metal was evident. You are not gong to find a meteorite in a river or stream. Experienced meteorite hunters do not look for meteorites in stream beds or along beaches .
I took the photo below in a glacial moraine in Antarctica known as “Meteorite Moraine.” This is a very special place, and hard to get to. There is at least one meteorite in the photo. Click here if you can’t find it. I am unaware of any meteorites having been found in glacial moraines of Europe, North America, or South America, although a couple of those from Greenland may have been from moraines.
2) Desert Pavement
Some deserts are good places to look for meteorites; others are not. Many deserts are paved with stones (alluvium) that have weathered off the surrounding mountains. Many meteorites have been found on desert pavements, but not many in North America.