By Lorraine Swanson
If you’ve noticed your Lake Michigan-tap water tasting and smelling like mildewed flip-flops lately, you’re not alone.
Taste-and-odor complaints of local tap water generally increase in the late summer, due mainly to the rich zebra mussel nutrients being deposited on the bottom of Lake Michigan.
That’s right, we’re talking about zebra mussel feces. Its presence becomes more noticeable in August and September, due mainly to the annual die-off of benthic green algae.
The invasive zebra mussel made its first appearance in the Great Lakes in the mid-1980s, when transoceanic ships from the Black Sea emptied their ballasts into Lake St. Clair.
Ever since then, the rascally bivalve has adapted nicely to our freshwater lakes and rivers, consuming planktonic algae by the gallon, clogging up water filtration plants, and wreaking havoc on the ecosystem.According to the DuPage Water Commission:
"Decreases in planktonic algae have resulted in increased water clarity, allowing sunlight to penetrate deeper, stimulating the growth of aquatic plants and benthic (bottom-dwelling) algae."
Zebra mussel nutrients on the lake bottom also stimulate the algae growth. The annual die-off of bottom dwelling algae in July returns high concentrations of “nutrients” in the water.
These "nutrients" produce compounds, adding that zippy earthy/musty flavor to our local tap water we've grown accustomed to in the late summer.
A female zebra mussel can release up to 100,000 eggs per year. They don’t have many natural predators. Ducks and certain types of fish have been known to eat them, but not enough to kill the invasive species off.
Most municipalities, including the city of Chicago, add powdered activated carbon into the water to rid it of that old flip-flop taste and odor.
Until science figures out a way to get rid of this mussel from hell, we’ll just have to put up with stinky tap water for a few weeks out of the year.
It’s not toxic, but unless you can’t get the image of zebra mussel feces out of your head, you may want to buy some bottled water or a filter.