A growing concern? Examining the influence of lawn size on residential water use in suburban Boston, MA, USA

Abstract In the US, households devote a considerable share of their annual water use to outdoor purposes. Existing literature suggests that residential lawns are a major driver of this outdoor use, especially in suburban settings. Yet this has not been tested using a broad-scope, fine-scale, and spatially explicit dataset. This paper presents a spatially explicit analysis of the relationship between household lawns and water use in suburban Boston for the year 2005, and extrapolates this relationship to the year 2030 under different scenarios of (sub)urban growth. We examine this relationship by employing two novel datasets: a 0.5 m resolution land cover classification of the town of Ipswich, MA and a town-wide household-scale monthly water billing dataset. Two scenarios of (sub)urban development in 2030 are explored, representing current trends and smart growth assumptions, using the land change model GEOMOD. Expected total annual residential water use is calculated for each scenario by extrapolating the relationship between household characteristics and water use from 2005 to 2030. We find that lawn cover, living unit density, and the number of bathrooms can explain 90% of the variation in annual residential water use. We estimate that Ipswich, MA could save 46 million liters of residential water use (a reduction of 5%) by pursuing a smart growth strategy. These modest savings are notable as they are achieved strictly through a densification approach to development i.e., the scenario includes no demand side management.