That muck is probably loaded with minerals and organic matter. You can see from how your plants responded that it was a good idea.
My base soil is tough adobe clay with virtually no organic matter. I have a compost pile and a small worm farm to generate organic material, nothing plant based goes to waste. My biggest issue right now is midnight raids from thieving animals.
The soil here is thin, and under it is solid limestone-the properties on this road have more dirt than most because of it washing in on the way to the river-but it is not rich soil-I usually add composted mulch, or even some purchased additive-this is the first year I’ve thought to add washed-in silt and muck from the river.
It is about the time critter raids here begin, too-I have a fence to keep out deer, but I’ve got to dig out the bird and raccoon netting to hang over the tomatoes and peppers-they like to bite into those, and the raccoons will strip all the ripe ones off...
thieving animals.........future compost ingredients............