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.