We are usually so preoccupied with the challenges we face today in managing rivers and streams, that we don't have time to think about whether there are big changes coming that we should start planning for now. Those changes can be both positive and negative. Before speculating on what might happen in the future, I think about whether such planning is even possible, and whether we can learn from our track record of prediction in the past. Whilst climate change is an obvious future issue, it is by no means clear how this can be built into present 'precautionary' decisions. Other issues include demographic and landuse changes, the secondary consequences of the actions we are pursuing now, and technological changes.