SEE why I asked for such measurements = It is the most common error done by most, to miss calculate heights and water velocities and as well water volume
It seems as well, that the stream at minimum level, like know, is producing around 1 cubic meter/sec
The initial measurements indicate that you have around 4 inches per 100 feet, water velocity seems to indicate that is the slope of the stream.
If you take 54 inches (1200 feet stream length) for 48 inches head and about 200 liter/sec, then
48 inches = 4 feet = 1.2 meters
Power availale (watts) = 1.2 * 200 * 6 = 1440 watts
How: 1200 feet = 366 meter of 12 inch= 300 mm sewer pipe USING AN IN-LINE propeller and a small DAM up stream for winter increasing the head by 1 or more feet ( each additional 1 foot= 300 mm head the power increases by 360 watts with the same water volume, but the water volume may increase ( if allowed) for maybe another 50 or so watts.
If a 14 inch = 350 mm and allowing around 300 liter/sec the power would be around 2200 watts
Other considerations would be to have a longer pipe run to increase the head, like 2200 for 22 * 1/3 = 7.3 feet = 2.2 meters
for 2.2 * 200 * 6 = 2640 watts
So you can see different ways to generate the power, AND notice that is GOOD for an IN-LINE propeller, that in winter the addition of a draft tube and a skirt may increase the power another 20 or so % .
basic design, and if you decide then more data is needed, it is doable if your aims and financial ( how deep the pocket is ) can handle it.
By the way, in USA and I believe in Canada, the CITIES change pipes periodically and those old pipes gotten by the asking or by the plastic price cost -- so think if your towns near you have such program .
You can make you own inline propeller with a Y coupler (the pipe - one side straight and the coupling at around 45 degree angle, I may have a sample in another hard disk.
Nando