In August we plan to start construction of our 2-2.5 acre pond. Have just about everything planned out, to the best of our knowledge, except for location. We don't know where exactly to put our pond.
Attached are two images ... (1) is a topographic map of our property and (2) one with the pond location. The property was mainly timber but in 2020 most of it was destroyed by a tornado. There is a fresh spring (very little output during the summer) that I'd like to build downstream of so it feeds into the pond. The general idea is to levee on the lower side (west) and overflow into the existing dry creek.
Your pics are now accessible. However, that topo map is very difficult to read online.
You are going to be spending a lot of money to build a levee/dam that long! You almost always get the biggest bang for your buck building the dam where the contour lines come closest together.
At the current location your pond is only going to have a small area with a depth of over 8'. I assume you will be excavating the pond basin for the dam material, but that is still going to leave a lot of the pond at 4' or less in depth.
As regards the spring, most people do NOT cover the spring in the pond if the topography allows room to avoid that. A spring can function as both an inlet and an outlet for water from the pond.
I would recommend moving the pond farther to the NW, downstream along your existing waterway. You can build the dam a little higher there, and still impound 2-2.5 acres of water - and your total yards of material moved to construct the dam might be significantly lower!
I would definitely prefer to leave the spring slightly above the normal pool level of the pond. That way you can observe the water flows from your spring. If the spring is flowing, but the pond level is going down, then you know you have a leak. Likewise, if the spring dries up during the summer, but the evaporative water losses in your pond are acceptable, then you don't have to spend the money to drill your water well.
Good luck on your new pond project! I think the house on the hill overlooking the pond in the little valley will be a great view.
Will you be on location while they are taking the soil samples?
You do NOT need 100% clay to make the core trench in your dam. It can have some silt and/or sand particles in the clay.
If you can be there, take a bucket of water with you. After they take enough material for the lab sample, you should grab a handful of the material that appears to contain clay.
Wet the sample a little bit. Can you roll it into a ball? Can you smush the ball on the side of your truck and have it stick? Can you roll it into the shape of a pencil? If so, then you have found your good clay.
Keep taking samples in your projected pond basin that would be adjacent to your dam location. If you can confirm good clay in a few spots in that basin, you should be good to go. If you find clay in another location, you should still be good, BUT your pond construction costs will go up because transporting clay to the dam location adds to the machine hours and diesel bill.
If you don't find any suitable clay material, then you are going to have to switch to Plan B.
This may be too late for you, but might help another reader. Here is a link to a series of video tutorials that walk you through getting a lot of valuable soil data from the USDA Web Soil Survey. Very valuable during the site selection process.