<P> A turning point came for development in the Everglades at the proposal in the late 1960s for an expanded airport, after Miami International Airport outgrew its capacities . The new jetport was planned to be larger than O'Hare, Dulles, JFK, and LAX airports combined, and the chosen location was 6 miles (9.7 km) north of Everglades National Park . The first sentence of the U.S. Department of Interior study of the environmental impact of the jetport read, "Development of the proposed jetport and its attendant facilities...will inexorably destroy the south Florida ecosystem and thus the Everglades National Park". When studies indicated the proposed jetport would create 4,000,000 US gallons (15,000,000 L) of raw sewage a day and 10,000 short tons (9,100 t) of jet engine pollutants a year, the project met staunch opposition . The New York Times called it a "blueprint for disaster", and Wisconsin senator Gaylord Nelson wrote to President Richard Nixon voicing his opposition: "It is a test of whether or not we are really committed in this country to protecting our environment ." Governor Claude Kirk withdrew his support for the project, and Marjory Stoneman Douglas was persuaded at 79 years old to go on tour to give hundreds of speeches against it . Nixon instead established Big Cypress National Preserve, announcing it in the Special Message to the Congress Outlining the 1972 Environmental Program . </P> <P> The Central and Southern Florida Flood Control Project's final construction project was straightening the Kissimmee River, a meandering 90 - mile (140 km) - long river that was drained to make way for grazing land and agriculture . The C&SF started building the C - 38 canal in 1962 and the effects were seen almost immediately . Waterfowl, wading birds, and fish disappeared, prompting conservationists and sport fishers to demand the region be restored before the canal was finished in 1971 . In general, C&SF projects had been criticized for being temporary fixes that ignored future consequences, costing billions of dollars with no end in sight . After Governor Bob Graham initiated the Save Our Everglades campaign in 1983, the first section of the canal was backfilled in 1986 . Graham announced that by 2000 the Everglades would be restored as closely as possible to its pre-drainage state . The Kissimmee River Restoration project was approved by Congress in 1992 . It is estimated that it will cost $578 million to convert only 22 miles (35 km) of the canal . The entire project was to be complete by 2011, yet as of 2017, the project is "more than halfway complete" and the new completion date is 2020 . </P> <P> Further problems with the environment arose when a vast algal bloom appeared in one - fifth of Lake Okeechobee in 1986, the same year cattails were discovered overtaking sawgrass marshes in Loxahatchee National Wildlife Refuge . Scientists discovered that phosphorus, used as a fertilizer in the EAA, was flushed into canals and pumped back into the lake . When the lake drained, the phosphorus entered the water in the marshes, changing the nutrient levels . It kept periphyton from forming marl, one of two soils in the Everglades . The arrival of phosphorus allowed cattails to spread quickly . The cattails grew in dense mats--too thick for birds or alligators to nest in . It also dissolved oxygen in the peat, promoted algae, and prohibited growth of native invertebrates on the bottom of the food chain . </P> <P> At the same time mercury was found in local fish at such high levels that consumption warnings were posted for fishermen . A Florida panther was found dead with levels of mercury high enough to kill a human . Scientists found that power plants and incinerators using fossil fuels were expelling mercury into the atmosphere, and it fell as rain or dust during droughts . The naturally occurring bacteria that reduce sulfur in the Everglades ecosystem were transforming the mercury into methylmercury, and it was bioaccumulating through the food chain . Stricter emissions standards helped lower mercury coming from power plants and incinerators, which in turn lowered mercury levels found in animals, though they continue to be a concern . </P>

What is the main source of phosphorus found in the everglades
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