I think your flow rate is too low to be practical. A nozzle to deliver 1 gpm is pretty small. leading to inefficiencies because the wheel would be too big for the jet of water to hit properly. In the Serious Microhydro anthology, the lowest flow rates are about 5-10 gallons per minute.
Here's how to calculate the power you'd get from a given head and flow.
flow in gpm times head in feet divided by 14 (10 for larger more efficient systems). Note that the head in this formula is the net head, which includes deducting the frictional losses in the pipe from the gross head.
So if you have 1 gpm at 35 feet of head, you'd only expect a couple or three watts, even if you could find a really tiny turbine. People in the Serious Microhydro anthology find that even a dozen watts is useful in an offgrid setting. 50 to 100 watts delivers a lot of energy, and a 200-300 watt system will deliver a high standard of living. That's off grid. If you already have electricity, hundreds or thousands of watts needs to be generated to make a system pay at a reasonable rate.
Anyway, this will give a good rough estimate of the power output at a given site. I do go into the technie gore details of how to get a pretty good idea of your potential output in Microhydro: Clean Power from Water.
There's a good discussion in the microhydropower buyers' guide, which I helped to create.
Here's the link:
http://canmetenergy.nrcan.gc.ca/renewables/publications/2427
Cheers,
Scotty