Any county of this state shall be eligible to submit a greenspace program for approval pursuant to the terms of Code Section 36-22-8 if such county:

(1) Has a population of not less than 60,000 pursuant to the United States decennial census of 1990 or any future such census; or

(2) Has experienced average population growth of at least 800 persons per year as measured by the population change between the United States decennial census of 1990 or any future such census and the most recent year for which the United States Bureau of the Census has prepared official estimates of population.

The Department of Natural Resources shall provide by regulation for the determination and notification of eligible counties consistent with the terms of this Code section.