The State of the Lake: The Consequences of Phosphorus Loading

Dr. Jeffrey Short
September 26, 2014
Special to the Lake George Mirror
 

The exceptional water clarity of Lake George has inspired praise at least since Thomas Jefferson first laid eyes on it in 1791—“as limpid as crystal,” Jefferson remarked at the time. This signature feature is largely preserved today, attesting to the high water quality of the lake. High clarity has, however, started to degrade over the last four decades, declining by about 6%. Although relatively modest, this decline is definitely real, based on thousands of measurements as summarized in The State of the Lake: Thirty Years of Water Quality Monitoring on Lake George, released jointly by the Darrin Fresh Water Institute and The FUND for Lake George—see fundforlakegeorge.org/StateoftheLake.

Measureable loss of clarity is almost certainly caused by increasing phytoplankton, microscopic plantlike algal organisms that absorb and scatter light in the lake’s surface waters. Phytoplankton abundance has increased by about 33% throughout the lake, mainly during summer and early fall. The phytoplankton increase is most likely the result of greater nutrient loading, especially of phosphorus. This increased loading ultimately comes from the increased numbers of people living in the Lake George Basin, generating more wastewater treatment discharges, using more lawn fertilizers and more household detergents, and intensifying stormwater runoff, all of which contain phosphorus in forms that can be used by phytoplankton to spur growth…

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