By 1993, the Everglades had been affected by numerous human developments.  The water flow and quality had been affected by the construction of canals and levees, to the series of elevated highways running through the Everglades to the expansive Everglades Agricultural Area that had contaminated the Everglades with high amounts of nitrogen.  The result of this reduced flow of water was dramatic. There was a 90 - 95% reduction in wading bird populations, declining fish populations and salt water intrusion into the ecosystem. If the Florida Everglades were to remain a US landmark, action needed to be taken.