Secure camera on sturdy tripod.
Set camera to HDR mode.
Set Aperture Priority Mode and aperture to f22, to capture flowing water. Use self timer to steady the camera as you shoot.
Camera takes three different exposures of the scene automatically. Use an HDR program like Photomatix or HDR Efex Pro on your laptop or desktop machine to combine the three exposures.
The final HDR image taken by the Canon 5D Mark III.