The Effectiveness of Urban Irrigation Day Restrictions in California

Abstract

We analyze the impact of restricting outdoor irrigation using monthly data from 408 urban water suppliers in California during the final years of the 2012–2017 drought. Our estimates suggest that assigning an additional no-irrigation day per week leads to a decrease in average monthly residential water consumption by approximately 0.8 gallons per capita-day. There is substantial heterogeneity in this impact. First, the marginal effect of a stricter irrigation policy varies depending on the existing level of outdoor watering restrictions — while initial restrictions lead to considerable conservation gains, tightening these measures further does not bring additional gains unless 6 weekly no-irrigation days are implemented. Furthermore, the policy is more effective in areas where residential water use represents a larger share of total urban water consumption and areas which perform better at reaching the 25% state conservation target.