Pond Boss Forums INTRO Questions & Observations leaking pond

Groundwater problem. We built a 3/4 acre pond a year ago. During digging, we hit water. Took pics during construction so we know where we hit water. Thought it was a spring, but turned out to be the water table. Spring rains filled it and it held most of the summer. Rains stopped, we hit a drought and the water fell about 3’. No leaks anywhere along the dam, I think the falling groundwater has sucked water out of it. Would bentonite be a good fix? Is it even possible to “isolate” a pond from the ground water table? Any thoughts or suggestions appreciated. Thanks!