There is a sense in much of the stuff out there that there are only a finite number of streams out there and they are in immediate danger of all being taken, I can not see how people come up with this.
In BC there are something in the order of 250 000 to 300 000 separate water courses, much depends on how you measure it. Most of these water courses have no established rights on them for anything. In large part this is because they are not close to anyone that would use them.
The most common reason water rights are owned in BC is for irrigation. It is not uncommon in the southern interior for there to be more water rights granted on a creek than there is water in the creek. What this means is that only those rights that can be exercised without out emptying the creek can be used.
Water rights were one of the first private property rights created in BC. In English common law you had a right to take water from a stream that went through your property. These are riparian water rights. BC created a different regime, a system of privately owned water rights not connected to any land, this is called Prior appropriation water rights.
For years there was a government policy not to allow any Crown Lands to be made into fee simple titles. This restricted private lands in BC. What was not restricted was the application for private water rights. In many areas of BC there are no remaining water rights for anyone to apply for.
The point of all this is to show that there are many other demands on water rights in BC and many have been granted, many times more than all the IPP applications.
The total number of locations in BC that have had rights requested for power development are only about 600 to 700. This is really a very small amount. The rights granted specifically grant conservation uses of the water priority over any other use - fish trump everything.
So you have the rights to the water - that is still a long way from making any power. The number of hurdles along the way are still significant. Unless you stay under 50MW, you end up in the environmental assessment process. You also need local government approval. You need to find financing. You need to be able to tie your project into the grid. There are many points along the way at which the project will fail to proceed.
How many IPP run of the river power projects will we see in BC over the next 20 years? Realistically about 100 to 150 producing about 18 000 to 25 000 GW/h of power per year. Most of the ideas for run of the river projects will simply remain ideas and nothing more.