Rain Gardens – View from an Economist

by Prof. Amy Ando, Guest blogger

Rain gardens, like other kinds of green infrastructure, capture rainfall that nurtures the garden plants and soaks into the ground (known as infiltration). Rain gardens can replenish groundwater and reduce stormwater runoff that would otherwise contribute to pollution and flooding during heavy rains. Adding rain gardens to a system of traditional curb-and-gutter stormwater management can reduce flooding, improve water quality, and nurture habitat for creatures that live in urban lakes, rivers, and streams.

Do these things matter? Yes. The values of flood reduction and water quality improvement have long been well-established. Our recent economic research shows that people would also value ecological improvements from green infrastructure. For example, we estimate that households in Champaign-Urbana would gain value of about $34 per year from green infrastructure that improved infiltration (and thus the aquatic habitat of nearby lakes and rivers) as much as possible (Cadavid and Ando 2013). We also find that people in Chicago would value a program that improved local aquatic habitat from good to excellent by an average of $23 per year (Ando et al. 2020).

The Red-Oak Rain Garden (RORG), however, is more than an improved way to manage stormwater. I walk through the RORG every day on my way to and from my office at UIUC. I always note with satisfaction how much water fills the rain garden during storms without flooding, and how quickly that water soaks into the ground over the course of the next day. But I’ve also paused at the rain garden to watch hawks and monarch butterflies. I’ve stopped in summer to look at the lovely native flowers that were planted as part of the RORG renewal project, and in winter to admire ice on the buttonbush nutlets that look like parts of a Dr. Seuss tree.

Research done with me by undergraduate Hanlong Zhang surveyed over 300 people in the UIUC community, and found they were willing to pay over $20 per person to have a large-scale conversion of current non-native plantings to native plants on the central UIUC campus.

Looking at the purple poppy mallows, it’s easy to see why.

Purple Poppy Mallow. Photo by Layne Knoche.

The RORG provides many important benefits to the community in its own location. It also serves as a model for the values that more well-designed rain gardens could bring to landscapes like the UIUC campus and its surroundings in the years to come.

Hanlong Zhang and Amy Ando. 2020. Department of Agricultural and Consumer Economics Honors Paper. “Estimating Willingness to Pay for Native Plants in the UIUC Community.”

Amy Ando, Catalina Londoño Cadavid, Noelwah Netusil, and Bryan Parthum. 2020. “Willingness-to-volunteer and stability of preferences between cities: Estimating the benefits of stormwater management.” Journal of Environmental Economics and Management. https://doi.org/10.1016/j.jeem.2019.102274.

Catalina Londoño Cadavid and Amy W. Ando. 2013. “Valuing preferences over stormwater management outcomes given state-dependent preferences and heterogeneous status quo.” Water Resources Research. https://doi.org/10.1002/wrcr.20317.

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