New Study Shows Artifical Turf Generates More Runoff Than Grass

A new study published in the journal, Science of the Total Environment, concludes that artificial turf lawns and xeriscaping generate more runoff than traditional turf lawns. The objective of the two-year study, conducted at Texas A&M over the two-year period from August 2018 to August 2020, was to "evaluate the total rainfall capture and runoff volumes generated...from several commonly used residential landscape types and to characterize the flow dynamics and peak flow of surface runoff in relation to rainfall intensity for each landscape."

 

Notably, the study was funded in part by Scott's Miracle-Gro Company, which obviously has an interest in keeping traditional turf, but the conclusions seem reasonable. The study ultimately states that, 

Beginning spring 2019, after plots were established and settled in, and through the end of the study, Sand-Capped Lawn and Mulch generally had significantly lower runoff volumes than all other landscapes. The native soil-based St. Augustinegrass Lawn maintained moderately low runoff volumes, while Xeriscaping and Artificial Turf each showed the highest runoff volumes.

The study caveats this finding by explaining that the sand-capped lawn and mulch both exhibited larger runoff volumes during establishment due to getting the sod to grow in the sand layer and the fines being washed out of the mulch. Their goal was to understand how more water efficient landscapes, which are becoming increasingly popular through water conservation efforts and rebate programs, would impact runoff characteristics. 

From professional experience, I know that artificial turf is becoming increasingly common around the Puget Sound region. To my knowledge, there is little regulation surrounding installation of artificial turf. In addition, little is known about the potential impacts of replacing lawn with artificial turf may have on our stormwater systems, local creeks, and water quality. 

Most of the information I found initially, when researching artificial turf, is from studies on the possibility for causing cancer from tire crumb rubber in sports fields. The EPA's final report was partially rolled out, but the data on potential human exposures was delayed because of COVID-19. 

Find the EPA's latest information here: Federal Research on Recycled Tire Crumb Used on Playing Fields | Safer Chemicals Research | US EPA

Even without the EPA's final report, artificial turf materials have evolved and are more widely accepted for sports use. During the 2015 drought in California, a bill was signed into law revising California's Civil Code Section 4735 and now prohibits HOAs from restricting the use of artificial turf. 

Similar to the efforts on understanding human health concerns, we now must work to understand the environmental impacts of artificial turf when it replaces grass lawns, especially in residential areas. I would not install artificial turf in my yard, and I hope you think twice about installing it yourself. While it has become widely accepted on sports fields across the U.S., I do not think it is wise to install it in our yards. With urbanization, we cannot completely avoid increases runoff but it is important to understand that replacing our yards with artificial turf could further increase runoff and create additional flooding problems in the future. 

Citation

B. Chang, B. Wherley, J.A. Aitkenhead-Peterson, et al., Effects of urban residential landscape composition on surface runoff generation, Science of the Total Environment (2021), https://doi.org/10.1016/j.scitotenv.2021.146977.