 The amount of agricultural and vacant land is decreasing as new residential neighborhoods are being developed around the periphery of Irvine, though on the other hand, the redevelopment of the El Toro air base as the Orange County Great Park will add to the amount of recreational land.The dry-season flow of San Diego Creek consists mainly of urban and agricultural drainage runoff.According to the Environmental Protection Agency, average dry-season flow at the mouth is , whereas wet-season runoff is .