INTERVENTION ANALYSIS OF WATER USE RESTRICTIONS,AUSTIN, TEXAS1

ABSTRACT: Mandatory water conservation in the form of restrictions on outdoor watering, car washing, and recreation was implemented in the City of Austin, Texas, during the summers of 1984 and 1985. Three different stages of restrictions were implemented limiting the number of watering hours per day, as well as a restriction that allowed lawn watering once every five days according to the last digit of the street address, Intervention analysis using a transfer function-noise model of daily water use is applied to assess the impact of the restrictions. Compared to a peak water use rate of about 170 MGD, it is shown that mandatory restrictions in 1984 reduced water use by an average of 13.5 MGD, while similar restrictions during the summer of 1985 reduced usage by an average of 5.5 MGD. Lawn watering restrictions on a five-day cycle produced a corresponding five-day cycle in water use of more than 10 MGD in amplitude in 1985. An alternative lawn watering scheme that eliminates this cycle is prescribed.