Pond Boss Forums GENERAL QUESTIONS Help pond leaking

Hi, I had a pond dug last summer, about 100x100, 14ft deep. The soil is clay and a little sandy. It's watershed.
It started to fill, got to about 4ft or so, stayed at that depth for couple months, then got a lot of rain, and it filled quickly, within a month or two. Now it is down to about 4ft again. I noticed it leaking about 3 months ago. It is leaking from the dam, don't see any holes from animals or trees. It's wet on the outside of the dam, stays wet towards bottom, about 20ft wide area.
There are trees around the pond, it was actually a wooded area that was cleared to dig the pond.
Was told it could be from filling so quick, that it didn't get time to seal, could that be it?
Did dump 2 bags of bentoite in it, may have slowed it down a little, or could just be wishful thinking on my part.
Can anyone give me any ideas of what to do next? Thank you, I appreciate your time.

That sounds more like a major leak. I don't know of anything you can do other than drain it and find the leak. Was it cored?

I'm not sure what you mean by cored.

Cored means a core trench which in the case of an earthen dam consists of a trench usually a bulldozer blade wide above and below the water level filled with well packed clay to act as a blockage to water movement through the dam. It sounds to me like the dam was poorly constructed and the core trench if present has areas of loose soil. Poor clay soil was used to build the core of the dam and or it was poorly compacted, possibly both.
http://www.whatpond.com/2009/07/core-trench/
http://pubs.ext.vt.edu/420/420-011/420-011.html
http://www.oregonaquaculture.org/documents/POND2007/Do's%20and%20Don'ts%20of%20PC.pdf
http://news.google.com/newspapers?nid=2199&dat=20030123&id=b4wyAAAAIBAJ&sjid=0ecFAAAAIBAJ&pg=4171,1298685

Many dug ponds have clay liners that are usually 2ft to 8 ft thick that line the inside walls of the pond. Often the clay liner is only in the upper soil layer that is not composed of heavy or dense clay. Entire pond bottoms in poor clay soil will have a clay hauled to the basin and compacted at least 12" thick. Those procedures are the process of building of a pond as opposed to just digging a hole.

He cut a key on the bottom, but on top I think he more or less just pushed the dirt/clay up on the dam and tried to pack it.

Most of the water then is passing through the poor weakly compacted soils used in the dam. The 'key' should have been extended to the top of the dam. Fixing a leaky pond can cost as much as the original cost and still the pond leaks. Choosing the best contractor who may charge a little more money is well worth the money if the pond does not leak. A leaky pond is a big headache.

Thanks for the info. The links were very informative, I appreciate your help.