Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Finding a leak?

This is my first post but have been following the site for many months. Lot of good info and ideas.
I had a pond dug in the fall of 2012. It's kidney shaped about 120' long with the narrow end about 30' wide by 10'-12' deep with the wide end about 50' and 20' deep. They didn't hit spring until 16'-18' down but started filling good. Soil is mainly hardpan/clay. They did run into a couple of areas of what I call "sand rock" which just crumbles when dug but they were packed in with the native soil.
Spring of 2013 pond filled but found the "watertight" Hancor elbow leaked at the welded seam. Why would you think that watertight actually held water??? Dranined water down and sealed weld and encased in cement. overflow pipe is down 7' below pond level. I'm glad I didn't have to drain completely. Water came back up but then started losing again.
After some research I determined that it was a leak and not all evaporation. I spread 7200# of granular Bentonite over the surface and it definatley stabilized the level and finally filled in December. During the start of spreading the Bentonite I was in the shallow end and stopped for lunch and realized there was a distinct 2-3' wide swath of "fines" being pulled toward the deep end. This indicated to me where we were leaking.
Now it has maintained until the last 2-3 weeks losing up to 1" per day then coming up as we get rain.
Finally my question; Is there a dye product that I can add to the water to see if there is a current that it pulls toward? I realize evaporation can be great but it seems like a lot to lose when we haven't had much warm weather yet.
Sorry for the long post. Thanks in advance for any input.

There is a pond dye called Aquashade, (there are other brands) and there are also water soluble packets that you can attach to a PVC pipe and stick below the water level and let the packet dissolve.

Sorry to hear about your problems!

I wouldmthink that natural convection currents in a pond will overwhelm the current a leak would provide unless the leak was horrible.

I would take a wild guess that the spring that was hit does not have the water pressure behind it to pump up to full level. Water can flow into a spring as well as out. You could try the dye test if you could dive down, stay still, and release dye right over the suspected leak.

Good luck, I feel your pain.

Thanks for your responses. I have no doubt the leak has been substantially reduced but I can't believe that evaporation is taking it down that much this early in the year. Is there a "most commonly" used formula to calculate evaporation? I've seen many thoughts but haven't come across one that seems tried and true. I know there are many considerations that go into the formula.

The best method is to put water into a container like a concrete mixing tub next to the pond with similar lighting. Observe the difference. The pond will typically be a little more loss since all ponds leak to some degree, a plastic tub is pretty water tight.

Very good idea. I will give that a shot this week and set the tub on top of the overflow so as to have it "in" the pond area. Thanks