Then, about seven or so years ago, the water level rose to the outer brink of the pond and there was only a very small beach near the front entrance, no sand beach around the pond, and even parts of the walking trail were closed due to the high water levels. The benches along the wall of the main beach were fully submerged and you could jump off the wall into the water.
That brings us to the past two or three years where the water level has continually gone done. Starting about four or five years ago the water began retreating from the outer limits and is now getting very low. When I went the other day there was a noticeable difference from even this fall's water levels.
Of course we're in a drought right now and I assume that accounts for a lot of the low water levels, but I decided to see what I could find about the low water levels and if the water levels have been this low in the past.
Walden Pond, which at 100 feet deep is the deepest pond in Massachusetts, is a kettle hole lake which was formed by retreating glaciers about 15,000 years ago. The main sources of water to Walden Pond are ground water and precipitation on the surface. Also, small amounts of water flow into the pond from the steep shoreline areas. (https://pubs.usgs.gov/wri/wri014153/).
It has been observed, including by Thoreau, that the water level does not correspond too much to precipitation, and this may be because the bottom of the pond is porous and therefore water levels are driven by water table levels, rather than by precipitation. It has also been rumored that there is a hole in the bottom of Walden Pond that connects to a stream that runs underground from somewhere in the White Mountains. (https://thecuriouspeople.wordpress.com/2014/10/30/the-hole-in-the-bottom-of-walden-pond-walden-129/).
In May a BU biology professor wrote a story about the low water levels for the Concord Tab and he wrote that the rising and falling water levels are not new to Walden Pond, and he features some Thoreau writings noting the same thing. (http://concord.wickedlocal.com/news/20160514/boston-university-professor-notes-low-water-at-walden-pond).
As a side note, but relating to the water, I once overheard two women talking about how the water at Walden Pond feels "softer" than normal water because of the pine needles that fall into it. I can't find anything about whether that's true or not but the water is certainly nice.
Whatever the reasoning behind the low water levels, this spring seems like it will be prime time to get a record swim time across the pond!
|Years ago you could do a shallow dive off of the rock steps. The rock steps (there are maybe 15-20 around the pond and most are usually closed off for restoration purposes) were highly coveted since they provided some of the only access to the water.|
|The cove part of the pond. This part used to be great for swimming and looking at fish and there was a pile of rocks to the left of where I am standing where lots of fish always lived.|
|You can see the water level markers in this picture from the current level on the left, to the brown stripe (grass and debris) in the middle, to the water's edge on the right.|
|For many years you could only swim to this point.|
|Maybe around 2009 or so the water levels were high enough that some kids were climbing out to the top of this tree and diving into the water. Pretty reckless at that point too but impossible now.|
|Another example of the water levels over time. This part is basically directly across from the bathhouse and it used to be really shallow water with a murky bottom but has just been sand for the past few years.|
|One of my favorite things about Walden Pond is that when you swim on a sunny day the light filters through the water perfectly. (It's better in real life than in the picture.)|
|And the water is very clear. You can see clearly for about 15 feet and there is still visibility beyond that.|