Ryan - .3" daily vertical loss and likely .10-.15" due to evaporative loss this Spring, so you may be looking at .2" daily loss due to dam seepage. I would seriously consider whether it's worth further investment of rehab or polymer chasing such a minor leak. Anything 1/3" or less daily loss we consider in the pond construction business as a successful project provided you're living in an area with decent annual precipitation [25" or greater]. It's your $, and I'll always help however I can, but if it were me I'd count my blessings and adopt a holding pattern.

However, your scenario is unique that you can't pop a well for supplemental irrigation and your watershed is limited, so if you elect to do pursue addressing the poor dam construction/seepage I suggest comparing the cost of core trench work vs. treating the dam face with a polymer application. I'd wager 3-4 units would address your dam seepage successfully at a fraction of the cost/time of rehab. I know you've already spoken to Drew Hay out of PA [one of the best pond builders on the planet], and he could likely provide a rough estimate on dam rehab project.

I'm glad your main basin is holding well following rehab and polymer - we just never anticipated your dam also being an issue. Reach out whenever you need me.