Appart from the mess left by some, there must be anglers who fish there over night, and even general conversation carries a long way in the dead of night which will wake the residents up close to the river.
on another note, anglers fished there long before the houses were built, so if it's a problem for them they should have given the location a bit more thought!!
you don't buy a house near a school, then moan about the kids making a noise.