This photo was taken on an overcast morning so a slow-ish shutter speed was inevitable. However, I really wanted to emphasize the motion in the flow of the water, so I mounted my 3-stop neutral density filter which allowed for a shutter speed of 8 seconds at F/16 ISO 100. The lens used was my Tamron 18-270mm VC, at 18mm.
Long exposures like 8 seconds are a matter of taste, but I love the painterly effect it can give. I find that the majority of ND filters on amazon are decent quality, and I usually don’t spend much more than $20 on mine.