Does anyone know of a publication or "site" that might give me the following information?
I have a 40 acre pond (not spring fed) It gets a little low when the rain is not available...
I want to add a well, pump and supply "make-up water to the pond...How many gallons per minute to maintain level of 40 acrea pond given appropriate variables...evaporation, etc....
Thanks, Walterb

I have seen a comment or two on how many gallons there are per inch of water per acre of surface area. If you know how much water you are losing overall (in inches over a week), multiplied by your surface area, multiplied by the number of gallons in an acre/inch all divided by 10080 (minutes in a week) you can show how many gallons you are losing a minute, which would equal the flow rate you would need from a well. I'll do more research and find a sample for you.

OK, found it. It takes 27,000 gallons to raise 1 acre 1 inch (Thanks to Brian Loberger in a previous post). Your 40 acre lake needs 1,080,000 gallons to raise one inch. If you are losing a quarter of an inch a day (hypothetical), you need 270,000 gallons per day to replace it. That would require 187.5 gallons per minute, which is one hell of a well. Somebody check my math, but that is about right. Of course, this all depends on what your actual loss rate is.

Formula is ((loss rate in inches per day)* (acres)* (27,000))/1440.

I would agree with that one, A WHOLE LOT OF WATER. 43560 sf acre mutiplied by .08 for 1 inch equals 3485 cubic feet multiplied by 7.481 gallons cubic foot eguals 26,070 gals/acre per inch.