If you want to use the spring as main water source for your pond, you need to build your pond lower the the outflow of your spring.
Springs are bi-directional. That is, they will push out water when the water table is high. They will pull water out of your pond if you build it over a the spring when it starts to run out of water.
My pond building experience is in the Shenandoah Valley, Blue Ridge Mountains, and Potomac Highlands of Virginia and West Virginia. My experiences may be way different than yours.
With that said, I built a pond below a spring that produced water most of the time from about October to May. Heavy summer thunderstorms and the after effects of tropical storms and hurricanes could get it running in the summer and early fall.
We built the one-third acre pond in about three days above my main 3/4 acre pond, for fishing, but also for flood control. The pond at full pool was about 100 feet vertically below the spring. The pond was also about 50 feet above full pool of my main pond, with small debris collecting ponds above and below the 1/3 acre pond.
These smaller debris ponds would trap a lot of stuff that can make your pond mucky. Most were smaller than 100 square feet of surface area, and between 1-4 feet deep during normal flow. I'd clean them out when the ground/water was thawed during the winter.
Being that we built this 1/3 acre ponds during the driest part of that summer, we found that we ended up being above the dry season water table. We built the pond with an 8-foot high dam, to have about a minimum of six feet of water during dry season, and about 7 feet during the wet season.
Within about three hours of pulling out the big 320 trackhoe, the D-6 CAT dozer, and the road roller out of the area, we began to see several inches of water above the deepest spot (about 7 feet below the top of the dam). By the next morning, this small pond probably had about 3 feet of water. That night we got a thunderstorm. The pond was at full pool the next morning.
We had installed four 10" x 25' pieces of corrugated PVC pipe at our desired water level. We built about a 10-foot wide spillway at one end of the dam with the bottom being about 6 inches above the bottom of drain culverts. We filled it with enough 6-7 rip-rap to be even with the top of the culverts mentioned above.
In the 6-7 years we owned that property, I don't remember it ever going lower that the bottom of the culverts. I'm not sure if the spillway ever had water above the rip-rap.
So, if your land can support a pond several feet lower than the spring output, you may very well have a very stable full pond.