Stormwater Runoff

Stormwater runoff is one of the main ways pollution reaches the Indian River Lagoon (IRL). Learn what it is, how it affects lagoon health and where those pollutants come from.

What Is Stormwater Runoff?

Stormwater runoff, also known as nonpoint source pollution, doesn’t come from one source (or point) but from everywhere in the watershed.

It’s the result of coastal development and the subsequent increase in impervious surfaces like pavement, roofs, driveways and sidewalks that don’t allow rainfall to soak into the ground.

In natural areas, most rainwater soaks into the soil or moves through plants back into the atmosphere. In developed areas, impervious surfaces prevent this infiltration, so much more water flows over land instead of into the ground.

Learn more about water quality and monitoring in the IRL.

How Does Stormwater Runoff Affect the Lagoon?

Instead of soaking in, rain collects and runs off into the nearest storm drain or canal, many of which discharge directly to the lagoon untreated.

Stormwater runoff carries an array of pollutants that increase nutrient loads and contribute to muck formation, chemical contamination, algal blooms and fish kills.

We’ve known that many stormwater runoff best management practices (BMPs), such as ponds and baffle boxes, do an excellent job of controlling solids suspended in stormwater.

However, these efforts often do a poor job treating nutrients like nitrogen and phosphorus that are dissolved in stormwater.

As a result, even treated stormwater can still contain high nutrient levels when it discharges to the lagoon.

Did You Know? A baffle box is an underground stormwater treatment structure with internal walls that slow water down so sediment, trash and debris settle out before the water flows to the lagoon.

Common Sources of Stormwater Nutrients

Nutrient sources in stormwater runoff include the following:

• Fertilizers from lawns, landscaping and agriculture
• Septic effluent
• Pet wastes
• Household and yard chemicals
• Lawn and yard wastes and other organic materials

Reducing these sources on land helps limit pollution in stormwater and supports a healthier IRL.

How You Can Help Reduce Stormwater Runoff in the IRL

Small changes on land lead to big results in the water. By managing what leaves your property, from fertilizers to pet waste, homeowners play a direct role in keeping stormwater cleaner and supports the lagoon’s long-term recovery.

In the IRL, stormwater runoff is part of a bigger story of excess nutrients and stressed habitats. Reducing pollution on land helps keep stormwater cleaner and supports the lagoon’s long-term recovery.

Explore how to live lagoon-friendly and keep harmful materials out of the ecosystem.