While excavating my barn site we came across a number of seeps/springs. They all seemed to run horizontally or uphill (flowing downhill). If I read your post correctly the land slopes upward from the seep.
I looked into developing the seeps for livestock watering and came across one method that might work for you.
Drive a well point or piece of 3/4" black iron pipe (with a threaded cap on both ends) into the ground horizontally starting at the wettest part of the seep. Pull the pipe out, remove the caps and reinsert it a foot or two short of the original driven depth. Compact the dirt around the area where you inserted the pipe as much as you can and as deep as you can. As long as the end doesn't get plugged the water should follow the path of least resistance and flow through the pipe. Then thread an elbow on the exposed end of the pipe and point it upwards. Thread another length of black pipe into the elbow so it also is pointing upwards.
If the vertical pipe fills with water to your full pool level then the spring probably won't reverse direction when your pond is full. If the vertical pipe doesn't fill you just wasted 20 bucks in pipe and 2 hours labor.
I'd compact the area with clay regardless of the results.
