Watersheds Explained

Everyone Lives in a Watershed

A watershed is an area of land where stormwater runoff will ultimately drain to a particular stream, river, wetland or other body of water. As individuals, our actions have a direct impact on the quality of our water resources. Stormwater runoff occurs when rain falls or snow melts and flows over the surface of the ground in the watershed. Hard surfaces like rooftops, driveways, sidewalks and streets prevent stormwater from naturally soaking into the ground.

The Problem with Stormwater Runoff

Stormwater runoff can pick up soil, trash, fertilizers, chemicals and other debris, and carry it into a storm sewer, which transports it directly to a lake, stream, river or wetland in your watershed. Anything that enters a storm sewer goes untreated into the same waterbodies we use for swimming, fishing, and drinking water. The way you take care of your home and yard impacts water quality.

Did you know that if yard waste, such as leaves, grass clippings, weeds, prunings, brush, and small twigs that are naturally found around the home, are disposed of along a creek or in the storm drain it can impact the water quality?

Yard waste decaying in creeks and rivers decomposes in a process that removes oxygen from the water. Fish and other aquatic life can’t survive in water with low oxygen. As yard waste decomposes, plant nutrients such as nitrogen and phosphorus are also released. These nutrients promote the excessive growth of algae in the water. As the water becomes polluted, it does not support aquatic life and becomes a health hazard.


Leaves and woody debris naturally accumulate in streams and creeks, however, when you collect and dispose of yard waste along creek banks, the added yard waste covers the ground and keeps out the natural vegetation that helps to stabilize the bank. This practice leads to increased erosion and sedimentation that clouds creek water and destroys habitat for aquatic life. Improper disposal of yard waste increases the accumulation of debris which in turn can lead to blockages that inhibit proper drainage. Although it is common for some homeowners to dispose of yard waste along creek banks, it is not good practice.

Erosion along creek bank
Erosion is evident along Deer Creek near Litzsinger Road in Ladue. Photo Credit: Litzsinger Road Ecology Center. © All Rights Reserved.