Weather and water quality?

Question

how does recent rainfall or lack of affect water quality

Answer 1

Your measurements should look at ppm.So the more rain should mean lower ppm.

Answer 2

rainfall (not runoff from the streams) should improve the water quality in general as it dilutes the pollutants. But I don't think it will be my much (a pond or water body with let's say 10-20 feet depth, a whole year worth of rainfall might just add 3 feet in most places in the world, unless the waterbody is a catchment of runoff from somewhere else, like streams). Lack of rainfall, can do the reverse, increase the pollutants level.