--no prior pond experience: check.
--decided to dig on a whim (with a borrowed trackhoe only available for short time last summer): check.
--no site or soil survey: check.
--dug right through clay soil and into sandy/rocky soil thinking "the deeper the better, right?": check.
--probably dug into some sort of ancient stream bed: check.
--hit plenty of springs: check.
--probably too steep of sides and levee: check.
--encountered boulders too large to move: check.
--water leaks out through sand seams underground and reappears in my pasture more than 100 yards downhill much to the delight of my farm animals: check.
--only found this informative website after-the-fact: check.

Luckily the pond is small (about 40 x 60ft) and there's a small branch creek which flows year round not too far away. I ended up leaving a large boulder in the middle like a little submerged island, and used it to place footings for my walkway (which is made out of black locust logs).

All of this was done on a shoestring budget, which makes it that much better. I did have problems filling the pond, and ended up using Soilfloc polymer which really helped slow the leaks. It still requires some continuous water flow from the creek, but I think that will be OK. I'm really trying to avoid using a liner.

I'm using 4 inch corrugated drain pipe from the creek for inflow, and a 6 inch corrugated pipe for outflow (which all goes by gravity downhill below the pond back to the creek). Will eventually slowly replace the cheap corrugated plastic with buried PVC pipe as the budget permits. I do have an emergency spillway. (One of the pictures shows some water below the dam, but the dam does not leak, and that is just spring water from some recent very wet weather which is unrelated to the pond.)

Welcome to the forum!

Very cool project. Where you have a source for free water, a little leakage may not be that big of a problem. Your steep sides could slough off and perhaps be a problem some day.

At any rate, it looks like a very enjoyable pond.

Thanks!, I'm really happy with how it turned out, and frankly I'm kind of surprised. It'll probably require some ongoing revision at some point, but so far, so good.

I'm a little leary about what might happen during a dry spell in the middle of the summer (for example, will the springs reverse direction and start leaking more water out of the pond?), I guess we'll see.

I think I'll wait at least a year before considering any stocking (rainbow trout).

Beautiful, That last photo...The Eagle has landed!!

How much did the Soilfloc help? How much did you use?

Without significant redesign of the pond, Soil floc is pretty much the only reason it was able to have any chance of filling. It previously leaked extremely badly, now just leaks, well, kind of badly. I'm lucky I have a very good source of free water coming in. If you have any large boulders, think twice about moving them. It seems like there is always sandy/gravel soil under them.

When I first tried filling the pond, I had a 4 inch pipe wide open flow, and was amazed to watch all of the water would nearly instantly disappear. (Again, this site and pond was going to be a challenge) I covered the sandy/gravel areas with clay as best I could (by hand with a shovel). I used 165 pounds of the polymer in multiple treatments and concentrated it over the areas where I knew it was sandy. You're not supposed to use it directly on dry ground, but I didn't have much of a choice and actually applied about 1/3 of it during very wet weather (in between rainstorms). Once it started to fill, I applied the remainder in 2 or 3 more treatments as the level continued to rise. Oddly, the last treatment seemed to make no difference whatsoever in the remaining leaks. You know whether it is going to work or not fairly quickly, but it seems to work for some leaks better than others. I still lose a lot of water but am able to keep up with it with the inflow.

As they advertise, it does give you a 'fighting chance' but it really doesn't make up for poor pond design very well. Do some calculations about how much you would spend on bringing in clay and heavy equipment, and what you would have to spend on this, and what you would have to spend on everything including this polymer if it doesn't work. Email the company and let them know your details of your situation.

Check: that one word made me laugh; Been there, done that.

what are your plans for the pond? are you going to add any fish? if so what kind?

The plan is to try rainbow trout.

Get some top to bottom water temperature measurements during July-Aug to verify if the water stays below 70F. If yes, you are good for using trout.

Thanks for all the replies! I think the cold creek water will keep the temperatures in a good range, but I'll get a thermometer and keep track.

By the way, with each heavy rain (which stirs up sediment from the creek), it seems to be sealing up better. I think I should get a 5 gallon bucket and take some measurements of inflow vs. outflow (through the drain pipe) in order to calculate how much is still leaking out. Placing inflow vs. outflow onto a graph will let me know if its changing over time.

Rainbow trout is cool! Add some shrimps too. Good job on your project.