Not sure what the new/correct function call is but updating line 64 to this worked ;)

//if (UnityEngine.Time.frameCount % detectionRate == 0 && WaterLevel.Factor(_supplyDrop.WorldSpaceBounds().ToBounds()) > 0.65f)
if (UnityEngine.Time.frameCount % detectionRate == 0 && _supplyDrop.transform.position.y < 0.65f)

That may work but I believe the correct function should read:

if (UnityEngine.Time.frameCount % detectionRate == 0 && WaterLevel.Factor(_supplyDrop.WorldSpaceBounds().ToBounds(), true, true) > 0.65f)

Yes, my post was just a quick 'down-n-dirty' hack begging for someone to provide the correct fix ;)