At a Glance

The influx of people coupled with the impacts of climate change has left the pond significantly altered from the days when Thoreau walked its banks.Sediments running off from trampled shorelines and human waste have fed certain kinds of phytoplankton that reduce the clarity of the water.

A Massachusetts pond made famous by one of America's most iconic writers is being destroyed by a combination of climate change, recreational activities and human waste, a new study says.

Henry David Thoreau wrote about his beloved pond in the masterpieceWalden,orLife in the Woods, a required reading staple for high school students across the country. Of the pond, the poet wrote that "; looking into which the beholder measures the depth of his own nature."

The success of thebook written in 1854 has drivenmillions of curiousfans from around to the world to visit the remote pond in the Walden Pond State Reservation, about 30 miles northwest of Boston.

Sadly, it appears too many people have been measuring their own nature at the shores of Walden Pond and have been found lacking.

The influx of tourists coupled with the impacts of climate change has left the pond significantly altered from the days when Thoreau walked its banks.

Researchers from Paul Smith's College collected core samples from the bottom of the pond and analyzed the remains of glassy-shelled algae preserved in the cores. Usingradio-isotopic dating to determine how old the cores were, they were able to document how the , according to a press release.

"The sediments of Walden Pond record major ecological changes to this iconic lake since the time of Thoreau. They also warn of more changes to come in a warming future," lead authorCurt Stager said.

The study published Wednesday in Plos One says when human recreational activities began in earnest.

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The evidence gathered suggests algal nutrient levels have changed because of sediments thatrunoff from trampled shorelines and footpaths and from human waste associated with swimmers. These nitrogen-rich nutrients have fed certain kinds of phytoplankton that reduce the clarity of the water.

The researchers note that warming temperatures associated with climate change will continue to exacerbate the problem in the years to come and warn managers that without a reduction in human-derived nutrients flowing into the pond, Thoreau's natural muse that he said was "the landscape's mostbeautiful and expressive feature" will cease to exist.