Have you ever been out exploring in a redwood forest and spotted a creek with oddly milky water? Perhaps light blue-green in color—and maybe even with some slight iridescence?
Quite a magical sight, isn't it? Like something out of a storybook or fairytale!
In areas with lush redwood forests—like here on the Mendocino Coast—many creeks, rivers, and even large long-lasting puddles can take on this unusual, yet oddly peaceful and alluring coloration during the rainy season.
One might wonder why!
Well, the answer is in the redwood tannins!
"Tannins" are chemical compounds that are found in all plants and trees, at varying concentrations. Different plants and trees have different tannins, with "tannic acid" being the redwood tree's choice. Found in redwood tree bark, heartwood and cones, tannic acid is responsible for providing decay resistance as well as protection against insects, fungi, and fire.
Interestingly, redwood tannins are not inherently blue. Rather, redwood tannins appear blue when they come into contact with iron in the presence of water, which causes a chemical reaction.
After several rain-less summer and autumn months pass, winter storms bring heavy wind and rains that shake free the several month's-worth of debris accumulation (as well as the occasional weary tree), thereby delivering redwood tannins directly to the forest floor.
California rivers and creeks, rich with iron, react with these redwood tannins. The result is a dark blue-black precipitate called "iron tannate"—which, when diluted with sediment-heavy runoff, can ultimately cause a cloudy creek to take on a milky turquoise appearance!
Fascinating, unusual and enchanting; so quintessentially Mendocino Coast!
Personally, I am mesmerized by the way sunshine seems to dance in-between the layers of iridescent water when light manages to penetrate the thick forest canopy and illuminates gemmy segments of a creek...
In parting, please enjoy a peaceful minute of tannin-saturated water flowing along Little North Fork Big River at Mendocino Woodlands State Park, a few weeks following major wintertime rainfall:
Comments