Posted by Richard B. Primack
As Henry David Thoreau noted 160 years ago, Walden
goes through multi-year cycles changing water level. This spring Walden Pond is exceptionally low,
with a broad expanse of sandy margins around much of the pond, and contrasts
with the pond’s recent high in the spring of 2010, when water entered the forest
around the pond and even flooded the p
aths.
Low water at Walden this year means a large sandy margin all around the pond
The past few years of low water have allowed alder
and birch saplings and wildflowers, such as lance-leaved violets and yellow wood
sorrel, to establish on the sandy beaches below the forest margin. When the
water rises again in coming years, this invading edge of plants will be
drowned.
Lance-leaved violets have established along the beach
Young alder plants at the forest edge will likely drown in future years when the water rises again
The water has fallen so low this year that part of a
submerged sand bar—one that Thoreau described in his survey of Walden Pond—is
now exposed. In Thoreau’s 1846 survey, he noted that the sandbar across the
mouth of what is now known as Thoreau’s Cove on the northwest corner of the
pond (the cove closest to the site of Thoreau’s cabin) was 7 feet below the
water’s surface.
Thoreau's Cove, a sandbar on the northwest corner of Walden Pond
Also related the low water level, the large vernal pool
near Thoreau’s cabin site, known as Wyman’s Meadow, has no standing water. In
typical years, the meadow fills with water in the late winter and spring, and mole
salamanders, American toads, and other amphibians lay their egg masses in the
water; later in early summer the pool is alive with tadpoles and juvenile
amphibians. By the summer’s end, the pool dries out and the meadow becomes a
carpet of colorful flowers. But this year, without any standing water, the
amphibians have no place to breed—and children visiting Walden will have no
tadpoles to catch.
Dr. Les Kaufman walks across Wyman's Meadow, which is uncharacteristically dry in 2016
The extreme low water and wide beaches that we are
seeing this year—an extreme that Thoreau noted too—is a part of what makes Walden
Pond so endlessly fascinating. Something to consider next time you take a stroll
around the pond.
You can read my full article on this topic in the Concord Journal by clicking HERE.
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