Arroyo Grande experienced rapid growth in the 1970s and 1980s, partially due to the expansion of the wastewater treatment plant, under an EPA Clean Water Grant, that removed a growth constraint. This federal grant program required preparation of an Environmental Impact Report, which provided much of the initial environmental database for Arroyo Grande. Arroyo Grande is located in a coastal ecosystem within the California floristic province, and the native habitats include coast live oak woodland, central coastal scrub, willow and mixed riparian along Arroyo Grande Creek and numerous tributaries, native bunch-grass grassland, coastal prairie, dunes and intertidal zone, and non-native and agricultural areas.