Here's another idea:
If there is clay beneath the loamy soils, depending on how deep the clay lies, you can excavate to clay, then use that clay to line the basin of your lake (Expense directly related to how much dirt you have to excavate) For smaller ponds and lakes, excavating is viable. Line the entire basin of the pond with good clay, 18-24" deep, compacted with sheepsfoot roller. Don't depend on the water table to fill the lake directly, as that is unpredictable. But, you can dig a sump adjacent to your pond/lake, and pump water from the uprising water table to keep your lake full. We've done that with smaller bodies of water, not necessarily larger lakes.
