Why is water usage declining across the United States?

To the residents of the draught stricken state of California, who are constantly being reminded to cut off the sprinklers and take shorter showers, it may come as a surprise that- according to a recent report by the Pacific Institute- water usage in the U.S. has actually declined between 2005 and 2010 across all sectors.

The Pacific Institute is an NGO based in Oakland, California that deals with addressing climate change, water shortages, habitat destruction and environmental injustice. Last week, the organization released a report using data from the U.S. Geological Survey (USGS) on water usage trends in the U.S. looking backwards from 2005 to 2010.

The report showed that total water usage in 2010 was at its lowest levels since 1970. In 2010, the U.S. used 350 billion gallons of water per day (bgd) compared to 440 bgd in 1980. The water usage per capita also declined from close to 1,300 gallons per capita in 2005 to 1,100 gallons in 2010, which was the largest decline in any 5 year period.  

It may be hard to fathom that water usage has declined as population and the economy have continued to grow; however, the report lays out ways in which regulation and water efficient solutions have counteracted this growth.

Looking at a chart of water usage over the past fifty years, there is a noticeable peak and then decline of water usage around 1980.

“In the early 20th century we were largely a manufacturing economy and much of the manufacturing was largely water intensive. Since that time, our economy has largely shifted to a more service economy, and much of the manufacturing we had a becoming less water intensive and a lot of that was because of the Clean Water Act,” said Pacific Institute’s Water Program Director Heather Cooley.

While there has been a decline in water usage for the past three decades, Cooley notes that the most recent data set from 2005 to 2010 was different.

“One of the things we saw, in particular, with this 2010 data was a decline in all categories. Not only total water use, but municipal, and industrial, in agriculture, and in thermoelectric power. The largest were in thermoelectric power, and that is an important reversal of a 25 year trend of increasing water use for that sector,” said Cooley.

Thermoelectric power plants can be fueled by fossil, geothermal, nuclear and biomass fuels and use a significant amount of the water for cooling the plants to prevent overheating. According to the USGS, thermoelectric power accounts for the largest user of water in the country, and in 2005 over 49 percent of total water usage is accounted for by thermoelectric power plants.

In the report, water usage in thermoelectric energy declined by over 20 percent between 2005 and 2010 from just over 200 bgd of water used to 160 bgd.

“There’s a shifting within that industry happening- in my opinion it’s not happening fast enough- but all new power plants in the United States use what’s called closed-cycle cooling instead of once through cooling… those regulations were put in place a little over a decade ago and that’s one good thing that’s happening in our water works,” said the National Resource Defense Council’s Director and Senior Attorney Steve Fleischli.

With once-through cooling, millions of gallons of water is sourced from lakes, streams, rivers and oceans to cool power plants. After water cools the plants, the water becomes extremely hot and instead of being reused is released back into the original body of water.

While closed circuit cooling can actually reuse the cooling water, rather than simply discharging it into the lake, river, stream or ocean, by evaporating the hot water in cooling towers. This process has been used on most new thermoelectric power plants since the 1970’s.                       

Moving forward

The Pacific Institute’s report may give optimism to those concerned about current water usage, but one may wonder what this holds for the future. Are we moving toward sharper declines in water usage or have we simply hit a plateau in efficiency?   

“I think it shows that we can efficiencies and improvements in our systems and still maintain economic prosperity, there’s still gains to be had… We’re still using water far less efficiently than we could be,” said Fleischli.

“We have certainly made a lot of improvements, but we have a lot further that we can go. We still use more on a per capita basis than other parts of the world,” said Cooley.

One way that the U.S. can continue to improve on decreasing water usage is by utilizing water efficient techniques as well appropriate pricing for agriculture. Agriculture is the second biggest user of water and the report shows that even as the amount of land irrigated for agriculture has increased, the amount of water use has declined.

Water usage for agriculture has been an issue of hot-debate in the state of California, as Governor Jerry Brown excluded agriculture, even though the sector accounts for 80 percent of water consumption in the state, in his executive order for California cities and towns to cut water consumption by 25 percent.  

“I think we need to price water for agriculture appropriately. And in many place we are not doing that,” said Cooley. “For example, in many areas for groundwater the only cost that’s being paid is the energy cost to bring it to the surface. So, there is very little incentive- except with the energy cost- to be using water more efficiently.”

Once water is priced efficiently, the market forces will drive farmers to become more incentivized to use already existing technology to maximize water consumption.

“One of the most important things folks can do is move toward drip irrigation and micro-irrigation of water and also making sure that crops get water when they need it the most… sometimes water is not delivered when the crop can use it most effectively.”