Opportunities to Reduce Regional Water Supply Gaps through Infill Development in Denver, Colorado

Across much of the Western United States, water demand is expected to exceed available supply within the next century. In Denver County, Colorado, this supply gap is projected to reach 24,700 acre-feet year-1 (3.05x107 m3 year-1) by 2050. Outdoor water use comprises approximately half of current total water demand in Denver, and outdoor demand is likely to increase due to increasing temperatures in the region. At the same time, more dense infill development of residential properties is altering the urban landscape and associated water use patterns. However, the impact of changes to outdoor demand associated with residential redevelopment on demand at the urban water systems scale is poorly quantified. The current work uses a statistical resampling methodology to simulate redevelopment of single-family residential properties into high-density, multi-family infill development and associated outdoor water use changes derived from a remote sensing analysis. Results show that infill redevelopment provides water savings ranging from 1.4-1.6x105 m3 year-1 per percent of single-family residences redeveloped. These water savings corresponded to a total of 7.6x106 m3 year-1 when 50% of single-family residences were redeveloped and a maximum savings of 1.6 x107 m3 year-1 when all single-family residences were redeveloped. Crucially, these savings comprised 25% and 50%, respectively, of the projected water supply gap in Denver for 2050. These results highlight opportunities for closing supply gaps by integrating land use planning with other conservation, demand management, and reuse strategies, potentially decreasing the need for new supply projects. Reductions in water demand should also be balanced against other urban management considerations to create more sustainable, climate resilient cities in water scarce regions.