According to the official reports, Everglades National Park in Florida was returned Friday to UNESCO's list of threatened World Heritage Sites.

The park is subject to "serious and continuing degradation of its aquatic ecosystem," said the World Heritage Committee of the U. N. Educational, Scientific and Cultural Organization. The Everglades was placed on the list of sites at risk in 1993 because of continued water quality problems and damage from Hurricane Andrew and removed in 2007.

It was also reported that the United States asked for the return of the park to the list and requested an evaluation later this year to help develop a conservation plan.

It has further been reported that the Everglades is a unique mix of saw grass prairie, mangrove swamp, tropical hammocks, pine uplands, bay and islands dependent on the "River of Grass" that once flowed unhindered out of Lake Okeechobee to Florida Bay. Efforts to drain swamps and dig canals for irrigation have interfered with water flow, and the park is also threatened by agricultural chemicals that cause algae blooms, killing marine life. (With Inputs from Agencies)