Question
Hello,

I am hoping that you can help me answer the following questions:

How much water loss due to evaporation and/or splashing can be expected or considered acceptable in (gallons and inches) during mid-summer days when the temperature is in the high 80's to mid 90's?  

Also is it true that waterfalls and streams contribute to water loss due to evaporation and/or splashing because of the water turbulence that they create?
 

The pond specs are as follows:

The pond is oval 14'6" Wide x 19'6" long.
The depth slopes from 3'8" to 2'8"
It contains 3150 gallons of water.  Measured using a hose bib meter when filling.
Head Height is 5'
The skimmer pump is rated at 6,000/hr at a head height of 5'
I have 35' of stream approximately 24" wide  (the streambed is covered with 1"-3" Delaware Boulders) The stream has 3 waterfalls that are each approximately 16" high The first waterfall originates directly from the bio-falls then there is 6'of stream (then waterfall) then 8'of stream (then waterfall) then 21'of stream to the pond equaling 35' of stream.

Thank you for your time.

Answer
Dear Al,

Thank you for your question.
However the answer is not that easy for me.
It has to much different items that can result in other information such as wind, open area, times of temperatures...
I think however when I look at our ponds this can result in A small loss of maybe one to A few centimeters. Waterfalls will indeed result in some more loss.just like the surface area also will result in more loss, especially when not that deep.
However, when you have A loss of many centimeters you need to think about leakage.
Maybe around the waterfalls where you often see some Los due to the natural effect of ... as I do not know the exact words see the image http://www.delftintegraal.tudelft.nl/info/images/080703035044020.jpg (sorry).

Hope this helps?

Kind regards,
Raf