The Color of Adirondack Water
by Mary Thill
Ed Ketchledge (1924–2010) was a botanist, but he was also a keen observer of things other than plants. On one of his many hikes in the Adirondack High Peaks he remarked that nowhere else in his mountain travels had he seen water the color of those gray-green streams.
High Peaks water is uniquely gray-green, but not in the cloudy way of absinthe. It is as clear and cool as a martini garnished with lichen.
Water has apparent color and it has true color. Tap water appears clear because algae and other suspended material have been filtered out. True color is hard to perceive in a glass-sized sample, but dissolved minerals and other components lend a subtle cast.
In the Adirondacks we have thousands of lakes, some of them true blue, some green and many classically Adirondack tea-brown. That clear-brown can indicate iron or dissolved organic carbon—basically life in its most micro, decomposed form. Green water can also indicate organic matter in the form of algae—and the return of life to water once rendered clear by acid rain. Or green can indicate pollution from too many lawns and too much fertilizer, or from nitrogen rained in from Midwestern power plants. Blue is the default color of the ocean and other large bodies of water that don’t contain much suspended material. NOAA explains that clear water absorbs colors in the red side of the light spectrum, leaving us to see blue.
The startling semi-opaque teal of the Niagara River above and below Niagara Falls comes in part from tons of dissolved limestone. The erosive power of the river scrapes a rock flour from the bedrock.
In Adirondack High Peak streams, the gray-green tint comes from a smaller-scale relationship between water and mineral. The underlying rock of the High Peaks is Mount Marcy anorthosite, which is dominated by a greenish-gray feldspar. A 20-ton block of Marcy anorthosite mined from the Cold Spring Granite Quarry, south of Au Sable Forks, is the cornerstone of the Freedom Tower under construction at One World Trade Center, in Manhattan.
This stone is rare on Earth but common locally, occupying more than 3,300 square miles, according to SUNY Plattsburgh, which explains in part why the Adirondacks look different from the Green and White Mountains, in Vermont and New Hampshire. This rock is the underpainting of the High Peaks forest, coloring the water and, sometimes, it seems, the air.