As the Southeast Florida area approached buildout, growth shifted to more rural areas in central and north Florida. Between 2000 and 2006, Flagler County was the fastest growing county in the nation, and both Osceola County and St. Johns County were among the 25 fastest growing;[24] Flagler County was identified as a Metropolitan Statistical Area on 18 December 2006.[25] The sharp growth in Flagler County (and neighboring St. Johns County) has had a negative impact on the Guana Tolomato Matanzas National Estuarine Research Reserve,[26] endangers wildlife such as manatees and bears,[27] and threatens the water supply for the region.[28]