Thanks AFB.  I tend to find the slower shutter speeds give a more attractive result - having said that, what counts as "slow" really depends on the rate of flow of the water.  these are all less than 1-second exposure because the water was flowing very rapidly.  Other shots I've posted in the past have taken 1-- to 30- seconds o get a satisfactory silky texture because the flow rate was correspondingly lower.  "Fast" shutter speeds have their place but for me I try to get slow enough to give a nice water texture.  By the way, the colour of the water is natural - very peat-laden hence the relish-brown colour.