Lawn watering in excess may contribute to flow in urban streams when more water is applied than plants can use or when sidewalks or driveways receive water from mis-aimed sprinklers.
Lawn Watering in Excess has Unintended Consequences
Lawn watering in excess of what plants need or misdirecting sprinklers to spray onto sidewalks or driveways may cause tap water to end up in urban streams. This could become problematic in arid and semi-arid cities during times of drought when water supplies are already tight – especially in urban and suburban areas in the Southwest – because summertime outdoor water use can soar to a whopping 60 percent of water use.
Researchers from Colorado State University and Kent State University applied a new approach to estimating how much of streamflow in urban streams in Denver, Colorado came from excess lawn watering and other urban tap water sources. By using a tracer that can detect the difference between tap water and local rain, the study evaluated 13 urban streams and two grassland streams in the Denver area.
Researchers found that, on the days they analyzed that had dry weather, over 65% of flow in urban streams was from tap water. Lawn watering contributed more than other tap water uses like leaks from water pipes (which accounts for 12 to 13 percent of household water use).
According to the study authors, this work can help water managers analyze water sources in urban areas and better understand the “consequences for water quality and water rights for downstream users.”