Stormwater Overview

A spring storm rumbles into Peoria, and our city gets soaked by an inch of rain.

When the system moves through, we shake out our umbrellas and go on about the day. But in streets, backyards, creeks, ravines, pipes, and tanks, the storm isn’t over - not by a long shot. All that water didn’t disappear. Here’s why.

Water, Water Everywhere

The way we've designed our public infrastructure developed our homes and businesses and sculpted our landscape over the past 125 years - and keep designing, developing, and sculpting - forces stormwater to go somewhere. That's when problems happen:

  • Combined sewers discharge raw waste directly into our most precious asset, the Illinois River.
  • Streams chew away at the soil, creeping closer to residential and commercial properties.
  • Streets flood, basements back up, and sinkholes form.

It's uncomfortable to realize that Mother Nature isn't the culprit here. We've changed the way stormwater can be absorbed with our manicured lawns, indoor plumbing, and ample parking spaces.

The Path of Stormwater

  • Step 1 - When wet weather hits, all that stormwater has to go someplace.
  • Step 2 - Landscaped surfaces, like grass yards, do a better job soaking up stormwater than pavement. But some water still runs off when the ground becomes saturated. Native plants with deep root systems are much "thirstier!"
  • Step 3 - Impervious surfaces, like roofs, patios, driveways and parking lots, absorb hardly any stormwater.
  • Step 4 - When stormwater runs off homes, businesses and other properties, it picks up pollutants and debris. Then it enters the larger system through inlets and drains.
  • Step 5 - Untreated stormwater travels through a pipe. This is also referred to as a "storm sewer."
  • Step 6 - Storm sewers are connected with manholes when there are changes in directions or elevation.
  • Step 7 - These pipes carry stormwater to outfall points, such as creeks. Channels of creeks and streams make up our larger watershed. When they are clogged and eroding, it can cause problems that nearby property owners may notice.
  • Step 8 - Peoria's network of smaller creeks and streams come together and drain into our area's most precious asset: the Illinois River.

More Pavement, More Problems

As our city has grown, adding new subdivisions and shopping centers so has our “impervious” footprint: more parking lots, roofs, patios, and driveways. These impervious surfaces don’t allow rain and snow to do what they normally do — soak into the ground. Instead, they run off into the sewer system or elsewhere.

Good Intentions Gone Bad

When property owners want to expand their yards or protect them from erosion, they tend to move the natural channel of water flow to the very back of the property. That shrinks the area water flows into and increases its velocity - like squeezing the end of a garden hose.

Changing the type of material water flows over (from natural vegetation to concrete) has a similar effect. It’s like sledding on grass versus sledding on ice. These well-intentioned actions can cause flooding upstream and erosion downstream.

Capacity Velocity Diagram