Cost share payments or loans pursuant to this chapter may be made for forest resource improvement work which is also the subject of payments or other assistance provided pursuant to federal law; provided, that payments or loans may not be made pursuant to this chapter to satisfy landowner cost share requirements of, or repay loans received pursuant to federal law; and provided, further, that the combined state and federal payments, and any required landowner cost share payments, do not together exceed the amount of the actual cost to the landowner or the prevailing cost per acre as determined by the director pursuant to Section 4801, whichever is less.