By the 1960s, urban development and agricultural use had decreased the size of the Everglades considerably. The remaining 25% of the Everglades in its original state is protected in Everglades National Park, but the park was established before the C&SF, and it depended upon the actions of the C&SF to release water. As Miami and other metropolitan areas began to intrude on the Everglades in the 1960s, political battles took place between park management and the C&SF when insufficient water in the park threw ecosystems into chaos. Fertilizers used in the EAA began to alter soil and hydrology in Everglades National Park, causing the proliferation of exotic plant species.[8] A proposition to build a massive jetport in the Big Cypress Swamp in 1969 focused attention on the degraded natural systems in the Everglades. For the first time, the Everglades became a subject of environmental conservation.[9]