Friends,
We receive many questions each summer about the solid cover of duckweed and green algae in the marsh. It’s timely now to think back about that, because there’s a connection between that and fall leaves.
The duckweed/algae cover is evidence of excessive nutrient washing into the marsh from stormwater runoff. It gets there via surface drainage or, more likely, by storm sewers. Storm sewers in our streets drain either to the river or to the marsh, depending upon where you live in La Crosse. So if you like to fertilize your yard two, three, or four times a growing season, some of that fertilizer is going down the drain. This time of year it’s nutrient from leaves, which are rich in nitrogen and phosphorous, just like your commercial lawn fertilizer. If you rake your leaves from your yard into the street for the city to pick up, then it rains, these chemicals leach out, run down the storm drain and some wind up in the marsh, there to feed duckweed/algae growth next summer.
You can prevent this, just keep your leaves on grass (the boulevard or your yard), your flower beds, or your vegetable garden. Free fertilizer! Just rake them into your garden and leave them at a depth of four to five inches. Out on your lawn, mow over them, chop them up and leave a light cover on your yard. Or pile them up and compost them. If you leave them on the boulevard the city will pick up and compost them. Whatever you choose, you are part of a biodynamic loop.
In addition, these leaves provide habitat for some common and necessary bugs: butterflies, moths, bees and other important pollinators winter over in the leaf litter.
The city's “Leaf It” campaign asks you to join in this environmental effort. So do we in Friends of the Marsh.