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The Colorado River Basin services the residential water use needs of nearly 40 million people. Residential use is the largest component of water use in urban areas, with outdoor water use representing a significant portion of a household’s water budget. The outdoor portion of residential use is often not reported due to most residences tracking all usage combined. This lack of data can be challenging when trying to regulate or pass policy that attempts to reduce outdoor usage. In this study the water use data of twenty-two urban areas in the Colorado River Basin Service area between 2005 and 2017 was retrieved from Hydroshare. These data were used to create Python functions that can estimate the per capita monthly outdoor water usage and display monthly and yearly water usage data. The outdoor water usage was calculated by finding the month of each year with the lowest water usage and then subtracting that value from the rest of the months in that water year. This estimation was done by assuming that the lowest monthly value is the average monthly indoor usage as it is used across each season. Results show a large variability in outdoor water usage between different population sizes and city locations. Cities that started implementing watering restrictions before 2017, such as Las Vegas, saw a steady decrease in water usage over the study period. Our future work will include examining a longer time frame of data from more cities in the river basin and seeing how various explanatory variables (population, region, climate, and policy) can help predict the outdoor water use in a city. This work can help quantify the amount of outdoor water usage for municipalities within the Colorado River Basin usage area and allow for urban areas to see the effects of water use reduction efforts.
Graduate student Civil Engineering, CU Boulder