Bender, I have a pond generally the size your looking at and maybe a touch bigger. Mine is between 1/10 and 1/4 acre. I am at 14 ft deep at the deepest and have a basin that is generally about 12-3 ft deep. To Bills point I had to go almost straight down with the sides. I drop straight down on the sides ( 4 ft deep ) to a 3 ft ledge going around on 3 sides of the pond. I then drop the remaining 9 ft straight down to the basin. I have one side of the pond that drops at a very aggressive slope of about 1.25:1.
Most of my soil is clay and I haven’t seen it drop to the 2:1 slope as mentioned, however I do have some of the side that have gone to more of a 1.5:1 slope.
All that being said, my bigger concern for you and for others trying this is that you can not compact the soil appropriately to hold the water effectively. I am fortunate to have a seasonal creek that keeps feeding my pond up until about mid July. Once I stop getting that feed, I show the significant seepage that you would expect from a pond that is not correctly compacted. Over time the seepage has slowed due to the pond filling in its own gaps and aging, however last year I was down about 3-4 ft due to this.
So what does that have to do with the price of anything??? Well you look like your planning on having a good deal of variety in your pond as far as fish varieties. Note the amount of fish the pond will support will be the same (x number of pounds ) no matter what variety of fish you put in there. Thus more variety the lower number of fish of any variety it will support. The other thing that comes into play is if you have the seepage that I would expect with a pond that can not be compacted correctly, then you will lose water volume and as such drive the fish into a smaller area and thus the total holding amount of your pond will also be less and you will have stressed fish and a stressed environment.
All that being said, I would have a contractor come in with a excavator to do the pond. You will not be able to get the depths you want in such a small area otherwise. I would also re-consider what fish you want in the pond. ( with aeration in my pond not going all the time, my surface temp is already near 68 to 70 degrees and my deep temp in about 56 right now. By mid summer my surface temp gets to be around 85 and deep temp is 70. I am near the woods with lots of shade and near Lake Ontario where I get a thermal cooling effect off the lake. Where I am going with this is that a pond that small may have issues with trout, unless you have a cool spring feeding it all the time ( then you get into the issues with spring fed ponds. ) you can find those issues on a diff thread.
I have YP and SMB in my pond ( about 100 perch and 25 SMB and I am considered to be heavily loaded for fish for a pond my size ) I was given guidance here to go with the YP and SMB combo as opposed to YP and LMB due to the amount of young produced and the desire to have a balanced pond where I wont have to worry about stunting as much as with other combinations.
Thus all in all I agree with Bill, I think you may have some pretty lofty goals for a pond that size and I would really look into what is best for the area you have and the conditions you have. I know that when I looked at it from that angle I found I have a much happier pond and a much more balanced Eco system that I do not have to do any work to if I don't want to. ( But I still mess around and make changes just for fun )
Good luck and keep asking questions here. The more you ask before you break ground the better the overall experience will be!!!
