Rainscaping

Definition

Acres of land treated for stormwater overflow using water quality best management practices

Why is it Important?

Rainscaping captures stormwater close to where it falls, preventing stormwater from causing sewer overflows, minimizing localized flooding, and improving water quality. Stormwater includes water from rain and melting snow. In urban areas, where there are many impervious surfaces such as pavement and buildings, stormwater can end up in sewer systems and cause sewer overflows, or flow directly into rivers and streams, carrying pollutants from roads and fertilizers from lawns with it. When stormwater cannot soak into the ground, it is also more likely to pool and cause localized flooding. Rainscaping addresses these issues by increasing the opportunities for stormwater to soak into the ground close to where it falls. For example, rain gardens use deep rooted native plants to make the soil more permeable so that it can absorb more stormwater. This process improves water quality because the soil filters the stormwater, preventing pollutants from entering water bodies. Rainscaping practices are known as water quality best management practices (BMPs) because they are the best ways to treat urban runoff and prevent water pollution. Other water quality BMPs include permeable pavement, rainwater harvesting (with rain barrels or cisterns), green roofs, vegetative buffers, and bioswales. This indicator measures the total land area treated with water quality BMPs through the Phase II Stormwater Quality Management Program. Currently, this indicator only measures water quality BMPs developed through the Metropolitan St. Louis Sewer District’s (MSD) program, though data for additional programs will be added as it becomes available.¹

How are we Doing?

As of 2022, 11,803 acres in the Metropolitan St. Louis Sewer District area have been treated with water quality best management practices (BMPs), which is 20 times the amount of land that was treated as of the baseline year 2010 (578 acres).

Geographic Level

The Metropolitan St. Louis Sewer District service area, which includes the city of St. Louis and 80 percent of St. Louis County (data for additional areas within the eight-county region will be added if it becomes available).

Notes

¹Under MSD’s Phase II program, all development projects in areas without a combined sewer system that disturb one acre or larger must address stormwater overflows through best management practices (BMPs). Developments that disturb less than one acre may also be required to implement BMPs as determined by MSD staff on a case-by-case basis. Not all BMPs are water quality BMPs; this indicator only includes water quality BMPs. This indicator does not include the rainscaping projects completed under MSD’s $4.7 billion Project Clear. This indicator also does not include rainscaping projects implemented through other programs or undertaken by individuals or businesses on developed lots.

Data Sources

Metropolitan St. Louis Sewer District