I was talking to someone with NRCS a few days ago and he mentioned that if we was to hit an underground spring when getting to the bottom depth of the pond during construction, then thats not really good. It would be nice if the spring is up higher and flows into the pond he said. I understand his explaining this but are there other options if we were to hit a spring low ?
Dig below it ?
Seal it ?

My pond is half the size I planned due to digging pilot holes and finding flowing springs at 7 to 8' depths in the area where the larger sized pond was planned. After finding the springs we would fill the holes back in and pac the clay as best we could. We also found the clays to be pinched out where the springs were.

Disclaimer: I am no expert. That said, if I hit a spring low down, I would attempt to intercept the flow outside of the pond basin and provide a route for the water to reach the surface and possibly run into the pond above the full pool level. I would then try to seal the spring off in the pond basin.

Thanks for the replies.
Sounds like I better make sure I hire a well experienced pond builder.
I dont know for sure there is an underground spring there. I do remember my neighbor telling me several years ago that there was a small spring over here on our property and I believe its where we proposed the pond to be.
Just trying to consider all options if this should happen.

Ground water follows the ground level. If you have a hill that is higher then the springs height at the bottom of the pond you may find that you get more pressure from the spring. This then will give you water and not take water. If there is an elevation change check that first.

Ground water if very funny. My neighbor drilled a well on the side of a hill. Hit a spring and now his well has a 3" drain tile that runs year round from his well to keep it from coming out the top of the well onto the ground.

If you find springs confusing, then think of them as tubes running from an outlet on the side of a bucket with water in it. If the top of the water in the bucket is higher than the pond water-surface level, then water will run into the pond. If the pond level is higher, then water will run out. The depth of water in the pond or the bucket has no effect on the direction of flow. Only the level of the top of the water in each has an effect. By placing the tube above the full-pool level of the pond, water cannot be sucked out of the pond no mater how empty the bucket gets.

We kind of ran into that when we put in our second pond. It is much like what Dono described above. This pond is dug into the side if a ridge (I live in the mountains).

We dug and dammed it in two days. All of the final dirt finishing was like watching line dancing between a D-6 dozer, a 320 excavator, and a big roller that looked like a big yellow hippopotamus. They pulled out about 4:00 PM in the afternoon.

By 7:00 PM that evening, the three sides dug into the ridge were all very damp. The bottom was getting very wet. There was probably a couple of feet of water in the bottom of the pond by the next morning. We then got a couple rainy days and it filled to full pool (7 foot deep).

Whether that is due to our natural mountainside water table, or a spring -- I'm not a hydrologist, so I don't know.

What I do know is that in the 5-6 years since it filled, no water has ever gone through the emergency overflow, but the has also never gone below full pool either.

Thanks for all the help.
Wow ! Sounds like it could go either way.
Like I said before, I think its in my best interest to get an experienced pond builder.
If I decided to get quotes soon then this is going to be one of the questions I bring up.