Camera: Nikon D3400
Lens: 70-300mm f/4.5-6.3
Shot at 70 mm
Exposure: Manual exposure, 2 sec, f/22, ISO 160
Flash: Off, Did not fire
Focus: AF-A, at 9.4m, with a depth of field of about 54m, (from about 4.3m before the focus point to about 50m after)
AF Area Mode: Auto-area
Already at F/22. I was curious because it was some good DOF.
Other than the above good advice, considering you already have the image.
If your software can do anything in relation to "highlight" you can lower the "brightness" of the white. When do waterfalls, etc the water really reflects the light and frothes up. So you get a lot of white in the heavily disturbed areas of water flow.