In Nevada, authorities have banned 'useless grass' to protect the water supply

Many parts of the United States are facing a water shortage. There is a likelihood of insufficient water supply at more than 200 watersheds across the country, according to research conducted by the US Forest Service. This is driven by climate change and population growth.

Without intervention, future shortages are expected to increase substantially, the report, published in the journal Earth’s Future, says.

Now, one US state is taking direct action, by banning the unused grass – on verges and outside offices and housing developments – that is sucking up water capacity.

Nevada Governor Steve Sisolak has signed a new law that mandates the removal of purely decorative grass from around the Las Vegas Valley by the end of 2026.

The legislation follows a period of several years in which the Southern Nevada Water Authority has offered rebates to landowners for replacing grass with less thirsty foliage.

The water authority estimates that there are around 5,000 acres of “non-functional turf” – grass that is not used for recreational purposes – in the valley. By replacing that grass with plants better suited to a desert environment, they could save 9.5 billion gallons (about 43.2 billion litres) of water a year.

Drought puts state at extreme risk

Nevada is experiencing extreme weather for the second year in a row, with 40% of the state in “exceptional” drought, the highest possible level.

This is a scenario in which reservoir levels are extremely low, with wildlife populations threatened and a significant fire risk.

In Las Vegas, residents are already under mandatory watering restrictions.

The Colorado River has shrunk to half its capacity since 2000. It feeds into Lake Mead, the largest reservoir in the US and the source of 90% of the drinking water for Las Vegas. The lake is at its lowest level since it was filled in 1937.

Nevada is not the only state at risk: neighbouring Arizona, Utah and California, which also rely on water from the Colorado River, are experiencing equivalent levels of drought.

The sponsor of the grass ban legislation, Nevada Assemblyman Howard Watts III, told the Associated Press that he hoped other states would take similar action.

“There’s broad acceptance in southern Nevada that if we can take some grass out to preserve the water supply for our communities, then that’s something that we need to do,” said Watts. “This sends a clear message about what other states need to be looking at in order to preserve water.”

A planet short on water supply

Climate change is disrupting water supplies in many locations around the world. By 2025, over half the global population will live in water-stressed areas, according to Pew Research.

This reduction in water supply relates not only to reservoirs, but also to groundwater. More than half of the world’s aquifers – bodies of rock or sediment that hold groundwater – are now no longer sustainable, because water is being extracted faster than it is replenished.

Analysis from the US Environmental Protection Agency suggests that increases in temperature, changes in precipitation, sea level rise, and extreme events could diminish water quality in many regions; with water insecurity ultimately having an impact on the reliability of food supply.

The western US is one area where droughts are intensifying. In Texas, which has experienced severe drought conditions multiple times since 2005, the Texas Water Development Board has earmarked $63 billion in water management costs to ensure that the state has sufficient water supply to support the needs of its growing population.

In Nevada, there is hope that the new law will help future-proof local reservoirs.

“It’s incumbent upon us for the next generation to be more conscious of conservation and our natural resources, water being particularly important,” Sisolak told the Associated Press.