Wherever leaves fall, they decompose and restock the soil with nutrients and organic matter.
But when there is no soil to land on — such as on a street or sidewalk — the leaves and all their decomposing bits wash down the street and into the storm drain. From there they go directly into lakes and rivers where the nutrients will feed unwanted algae growth next summer. In addition to a major "ick" factor, this algae is a problem because when it dies and decomposes at the bottom of the lake, it uses up oxygen that fish and native plants need.
In the Mississippi River-Twin Cities Watershed, the MPCA monitored and assessed 180 lakes, and 80 of them didn’t meet water quality standards because of excess nutrients. And leaves are a major source of the problem. Depending on the lake, leaves might account for 60% of the excess nutrients in these lakes.
Don't "leaf" it up to someone else to solve this problem! Here's what to do with your autumn leaves so that they nourish the soil and not unwanted algae.
Rake the leaves that have accumulated along your curb, sidewalk and alley
Several times during the fall, rake up the leaves that have accumulated along your curb and sidewalk. Street sweeping in late fall helps keep a lot of leaves from entering the water. If your city doesn't already do this, encourage them to start! By the time the street sweepers drive by, however, lots of decomposition and several rain storms may have occurred. You can help by raking 1-2 additional times. If you work with youth or community groups, consider organizing a community clean up for water quality to do this for others. Never rake leaves into the street, even when you know the street sweeper is coming.
Never trash or burn your leaves
Don't add leaves to the regular trash (it's illegal!) and don't burn them. Burning leaves releases large amounts of air pollution. These pollutants can cause breathing problems for sensitive groups and lead to long-term health effects for all of us.
Put leaves in your backyard compost pile
One of the best ways to use leaves (from the street or the yard) is to compost them in your backyard. Learn how to compost in your backyard.
Tip: If your bin isn't big enough to accommodate all your leaves, put early and late season leaves in the bin, then on your main raking weekend bring the rest to a compost or yard waste drop-off site. If you have room, also bag up and store some dry leaves to use as a carbon source ("browns") in your compost pile during the coming year.
Use leaves to mulch your garden and lawn
Whole or shredded leaves can be used as mulch. Mulch benefits the soil and reduces weeds. On the lawn, use a mower to break apart the leaves so that they fall between the blades of grass (consider using an electric mower, since gas lawn mowers, especially older models, produce large amounts of air pollution). Don't let the leaf layer get too thick! In garden beds, leaves provide a protective layer of insulation for perennial gardens and shrubbery, either bagged or loose. Read these additional tips for mulching from Minnesota Extension.
Drop leaves off at a compost site
Another option is to drop off your leaves and sticks at a compost site near you. Depending on where you live, these may be called “yard waste” or "brush” drop sites. Contact your city or county for drop-off site locations, items accepted and any fees involved.
Consider curbside pick-up if you want a convenient option
Your garbage hauler may separately collect yard waste — sometimes for an additional fee — and then bring it to a commercial compost site. Contact your garbage hauler to learn about your pick-up options.
Be aware that residents in the Twin Cities area who bag their yard and organic waste are required to put their waste out for pickup in compostable bags — either paper bags or compostable plastic bags. This law applies to residents in Anoka, Carver, Hennepin, Ramsey, Scott and Washington counties. Learn more about the compostable bag requirements on Rethink Recycling.
Play in your leaf pile
Before bagging or moving the leaves, jump in them! Inhale deeply. Share your pile by leaving it on the lawn near the sidewalk for a few days with chalk note that says, "jump!" There are tons of benefits to playing outside including boosting vitality; improving vision; reducing risks of heart disease, obesity, bone problems, depression, and stress; reducing the symptoms of attention deficit hyperactivity disorder; and more.