Fall Tasks for Year-Round Water Quality

December 4, 2024

By Erin Parker, Interpretive Services Supervisor

Late autumn’s charms are perhaps subtler than other seasons. Walking in the woods and seeing all the nests (birds, squirrels, and wasps!) visible on the skeletal trees. Hearing owls calling in the early evening, as darkness sets in at 5 p.m. and doesn’t lift again until after 7 a.m. Activity at your bird feeders and in your garden, as cooler weather attracts hungry birds to the seeds.

While the majority of our yard, garden, and landscape tasks are complete ahead of the first hard frosts, there are still chores that we can do to keep our local waterways clean year-round. And these same tasks help keep our streets from flooding during the first snow melt or heavy rain.

Fall tasks, year-round water quality

Homeowners and property managers are often reminded to “leave your leaves”, that is, to use the natural debris as slow-decomposing fertilizer and mulch in your garden beds and providing overwinter habitat for insects and other wildlife. But leaves do blow around, and keeping your local storm drains clear of leaves provides multiple benefits.

First, our lakes and streams receive a deluge of leafy material this time of year that contribute nutrients like nitrogen and phosphorous. These nutrients are important in small quantities, but large amounts lead to algal blooms in the spring and summer. The algae’s short life cycle means that it quickly dies, often sinking to the bottom. There, decomposing bacteria utilize oxygen while they break down the dead algae (and the original leaves), but this, in turn, leads to a low-oxygen zones where fish and other aquatic species struggle to survive. We as humans see this in spring fish kills and in the strong, unpleasant odors of decomposition in the water.

Second, removing leaves and debris (both natural and human-caused litter), keeps the storm drains clear to do their job- moving water off roads, parking lots, and sidewalks. Drains clogged with leaves or litter can become backed up, especially as temperatures drop and accumulating stormwater freezes around the drain instead of draining away. This also helps when and if we get any snowfall during the winter, as that snow melts, clear and clean drains can function as designed.

Fall chores like fertilizing lawn and turf grass can also be done to minimize harm to our waterways- just as fertilizers increase the growth of grass, once they wash into a lake or pond, they can also support growth of aquatic plants and algae. Using only the minimum amount of fertilizer, don’t apply when the ground is frozen solid or the soil is saturated, and clean up any that falls on hard surfaces such as driveways and sidewalks. Michigan has a law that requires phosphorous-free fertilizer be used for most residential and commercial lawns. This law, intended to protect waterways, fisheries, and all of the recreational opportunities on and around water, mean that phosphorus-free fertilizer options are readily available in Michigan.

Cleaning up and properly disposing of pet waste also becomes particularly important this time of year and into the winter. As the ground freezes, anything left on the surface is more likely to be washed off into the storm sewers instead of slowly breaking down into the soil. Pet waste can contain E. coli and other bacteria that can cause beaches to close, recreation opportunities to be limited, and even harm the health of people and other pets exposed to contaminated water.