I'm not an expert on artesian flow and wells but here are few things to consider:

The book may say you can raise 400 lbs of trout on 8 gpms but I think that is extremely optimistic! Once this amount flows into a pond it loses it's power to keep the pond cool enough in summer if there are no other migitating factors. The rule of thumb trout farmers use is 10 to 20 lbs. of trout per gallon of flow. I harvested 500 lbs of trout out of my 1/10th acre pond last fall w/ a flow of about 38 gpms.

That said, you may be able to find more flow by digging etc. I would contact a state geologist or someone that has experience in this.

Another point is you may have much much more potential by boring a well if you have water that is confined under pressure in your area. A friend in Ohio that has a trout farm bored two 8 inch wells through a confining layer of limestone and now has 1500 gallons of free flowing ground water whenever he wants it. He has too much actually, and diverts the excess to an adjacent river. But interestingly exactly where he drilled was crucial as this ground water ran under the limestone in veins and a few feet over hardly produced any water.

Just some points to ponder. You can never have too much flow except maybe in the previous case!

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.