leak or seep? problem or not?

I have a pond on my property that's fed by a small creek. The creek is usually two to three feet wide and an inch or two deep. It runs all year. There was recently work done on the dam. The pond was drained while the dam work was done. When it was refilled I noticed there was a wet spot on the back side of the dam. It's not near the center of the dam where there is a drain pipe to a creek, it's more off to the side. When I pointed out the wet spot to the man who did the work for me, he said they noticed some water coming out of the ground when they dug down a couple feet so they could pack the main dam area with additional red clay. I think they may have created a seep. I have seeps on my property, but I had not noticed one within a hundred yards of the pond before the construction. He said when they laid down and packed the new additional clay, the water coming out of the ground disappeared. I'm trying to give you back story but maybe it's TMI.

Anyway, I'm in SC and we have had enormous amounts of rain (biblical proportions). The pond has held beautifully, never even close to flooding. The design of the drain pipe is another whole story but it's AMAZING!!!

Here is my question. The wet spot hasn't gone away. A small trickle of water is definitely forming and runs continually off to the side of the dam. The level of the pond stays stable except when it rains and the level goes up until the drain design kicks in and starts pumping water out. From just looking at the normal drain rate, the water in equals the water out. So,

1) should I be concerned about the wet spot and the trickle of water if it is a leak? I've thought about putting dye in the pond to see if the water in the trickle shows signs of the dye. (Then I think dye is probably not good for my pond)

2) if the water is seep water, should I be concerned about that wet spot compromising the integrity of the dam, or causing a leak eventually ?

Sigh. TIA for any suggestions

I understand that the dye that you would use to do this would not harm your pond. These dyes are biodegradable, like food coloring. My father, who used to be a water system technician for a small city, used dyes like this to locate problems.

I would keep regular observation and data of the leak area, especially after up slope rain events or increased flow rates in nearby creeks and springs. It would be difficult to document the exact water coming in and out of a pond that is naturally lined on a property with seep springs, as the pond will be saturating the ground, raising the water table, and possibly connecting water sources.

Without seeing it or observing your land at all, my guess is this: When the excavator keyed the dam below where it was before, they could have tapped into a seam that was running between two clay layers and was not visibly present before they began work; this underground water course was running underground to some seep or spring down slope away from your dam site. Now that that seam has been packed with the dam key it is saturating the material of your key and has found a way out, heading down slope out of the dam. There is all kinds of potential for your dam to fail.

A couple things to think about and observe:

What you might want to consider is how thick your dam is in relation to how much is being saturated by the seep.

It might cost you a couple or a few hundred bucks to get a hydrologist of merit to check it out, but that may be well worth the piece of mind.

I've been reading up on bentonite clay. Available in 50 pound bags. Well drillers use it.

Sprinkle it in the water over the seapage area. It will get drawn into the leaks, carried by the water flow, and expand 10 times it's size to seal it.

It's used in landfills to lock out the toxic goo from the groundwater.

There was something mentioned about it getting clogged into fish gills on a temporary basis, if that's a concern.

Thank you for the replies. Some people call me a procrastinator but I prefer to think of myself as thoughtful. So, I've been thinking about this and getting a consult is a very good suggestion but I'm on a tight budget. I'm keeping my eye out for a person with those skills who would consult at a rate I can afford.

The bentonite sounds promising. I will do some research on cost and methods.

I've shied away from the dye because I don't want to put something in the water that will show up down stream. My pond is fed by a stream and there is no way to keep the dye out of the stream if I put it in the pond.

In the mean time I've had a couple ideas about trying to determine the origins of the wet spot.

I can drain the pond. I can do that easily because of the WONDERFUL design. All I have to do is cap the air flow pipe on it and it will start pumping water out like a fire hose. Because I am a "thoughtful" person I haven't stocked the pond so I can still drain and fill it without my emotional or financial woe. The goal would be to see if once drained, the wet spot went away.

Is it possible that the wet spot is a seep and that the weight of the water in the pond is forcing the seep to surface at the wet spot? I think that's what Joe was alluding to. So, if I drain the pond and relieve the pressure on the seep is it possible that the seep will revert to it's original path and the spot will dry up? It that's the case I'm back to square one because the wet spot will come back when I fill the pond again. On the other hand if the wet spot stays I know it's a seep!

If the wet spot is a seep and not a leak, does anyone have any ideas about how to address that? The man who worked on my dam said he thought the easiest approach is to dig a drainage ditch/swale and put gravel in it. The flow would be directed back to the stream. The problem with that is that is doesn't address the wet spot affecting the integrity of the dam.

Maybe the answer is to apply the bendonite to the inside of the pond on the other side of the wet spot, and to do a swale?

Would it matter if the pond failed? I mean, would it damage anything downstream? Is it a few feet deep? Or dozens of feet deep?

The pond is maybe a quarter acre and is about 12 feet in the deep end. There is nothing immediately downstream that would be damaged.

I had a pond dug that was maybe an eighth of an acre and six feet deep. I had not finished armoring the whole spillway slope when we had the worst flash flood in 50 years or so. The whole pond went down the little ravine it feeds and scoured things up all the way to the main creek. Yours, depending on the height of the dam, could do a lot of damage even if there is not a human structure in its way, and for a good distance downstream, especially considering that if it gave it would probably be during a heavy flow event.

A critical factor would be how close the seep is to the toe of the dam.