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article imageThe reason why some lakes are getting murkier

By Tim Sandle     Dec 11, 2016 in Environment
A study of some 5,000 lakes in Wisconsin has found over a quarter have become murkier over a twenty year period. The rate of murkiness is expected to increase with global warming.
The reason for the lakes becoming murky relates to the level of precipitation and the run-off of water from agricultural soil. This is the finding from recent research conducted by scientists based at the University of Wisconsin-Madison and the Wisconsin Department of Natural Resources.
The finding forms part of a research project and the data was largely gathered by citizen scientists, together with assistance from federal agencies. Data was gathered over the course of two decades where observations were made about water clarity and significant changes to the landscape within the vicinity of the lakes. Notes were also made relating the climate conditions, such as temperature and rainfall. Changes to climate, as a product of global warming, can lead to increases in rainfall.
The inference is that years when rainfall is heavy (‘wet years’) adversely affect lakes that have greater water clarity. Such lakes become vulnerable to plant matter and nutrients running off from agricultural fields. This helps turn the water brown or green in color. The main variable, helping to reduce the discoloration of water, is the buffer around the lakes.
There is a solution to the problem and this involves reducing the amount of agricultural land immediately surrounding Wisconsin's waterways. This should limit the degree of water run-off and lead to an improvement with water clarity. In essence the landscape in this, and similar areas, requires adaptation as part of future plans.
According to the lead researcher, Dr. Monica Turner the limitation of farming is the answer, increasing the buffer between agricultural land and lakes. In Wisconsin the buffer is formed of vegetation immediately adjacent to a body of water. This is termed the riparian buffer. The researcher notes that protecting the buffer also benefits farmers since it helps reduce the damage to crops from heavy rainfall.
The research has been published in the journal Ecological Applications. The paper is titled “Annual precipitation regulates spatial and temporal drivers of lake water clarity.”
More about Climate change, Global warming, Lakes, Great lakes
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