Study Raises Concerns About Wastewater Reuse
A new study published Wednesday by the National Academy of Sciences says there is enormous potential in wastewater and stormwater recycling. But it warns that existing regulations may be inadequate to ensure these water sources are adequately sanitized.
“This is water you have now that you can take advantage of,” Richard Luthy, a Stanford professor and one of the report’s authors, told the Los Angeles Times. But, he added, “there’s the opportunity there for exposure to pathogens. And that’s something that needs to be studied more carefully.”
The biggest concern the authors found is the absence of risk-based guidelines that ensure water quality is protective of public health. Rigorous, risk-based guidelines could improve safety, reduce spending on unnecessary treatment and assist communities that lack an existing regulatory framework for onsite water supplies.
The authors recommended that the U.S. Environmental Protection Agency, a collaboration of states or a collaboration of U.S. water organizations working with EPA develop these guidelines.
Right now, there is substantial variation in onsite gray-water and stormwater regulations at the state and local levels. Regulations have not evolved quickly enough to keep up with advances in technologies and their use, hindering the capacity for gray water and stormwater to significantly expand the nation’s water supplies.
The report recommends best practices and systems for the capture and use of stormwater and groundwater. For instance, although the authors support simple gray-water reuse systems to irrigate landscaping, they say it should not be used “in arid regions to support landscaping that is not sustainable in the long term.” Instead, water-efficient landscapes that are appropriate to local microclimate would be more appropriate and might not require irrigation at all.
The timing of the report is fortuitous, since the Los Angeles metro region is considering construction of what would be the nation’s largest wastewater recycling system. At an estimated cost of around $3.5 billion, the project would purify as much as 168,000 acre-feet (207 billion liters) of treated sewage annually and use it to supplement regional drinking-water supplies.
That plan is already drawing scrutiny from San Diego officials, who fear it is too costly and too risky.
State Releases Drought Videos for Kids
The state of California’s official water conservation website, Save Our Water, has released a series of educational videos for children.
The three-minute videos will air on public broadcasting stations in California and are available on the campaign’s Vimeo page.
The videos are produced in partnership with Curiosity Quest, an award-winning PBS program for children that focuses on science and technology matters.
The videos ask children as well as experts about water-saving tips. One video, for instance, recommends removing unnecessary lawn, such as the strips between sidewalk and curb; choosing the right water-saving appliances; and changing personal habits.
“It is important that programs like Save Our Water reach out to younger audiences,” Jennifer Persike, deputy executive director of external affairs and member services of the Association of California Water Agencies, said in a news release. “Curiosity Quest was an ideal partner … to help educate children on what they can do around the house to conserve.”
Save Our Water is a partnership between the California Department of Water Resources and the Association of California Water Agencies, which represents about 90 percent of the urban water utilities in the state.
Fewer Trees Means More Water. Right?
That has been the assumption made by some people, who reckon — through simple logic — that thinning overgrown forests will reduce demand for water, since there will be fewer thirsty roots slurping it up.
But not necessarily.
A new study by scientists at the University of Utah concludes just the opposite: As trees die, compensatory processes kick in that may actually reduce water availability. When large areas of trees die, the forest floor becomes sunnier, warmer and windier, which causes winter snow and summer rain to evaporate rather than slowly recharging groundwater.
The study focused on trees killed by pine beetles, a phenomenon that is aggravated by water scarcity. Lead author Paul Brooks, a geology and geophysics professor at the University of Utah, said the study is the first empirical evaluation of streamflow response to widespread tree mortality from mountain pine beetles in more than 30 years and is the largest study of its kind.
Brooks presented this research at the American Geophysical Union’s annual meeting in San Francisco.
The researchers monitored streamflow changes in a number of basins after large beetle-induced tree die-offs. Streamflow decreased in three basins by 11–29 percent, with no change in five others.
The results are “consistent with increased transpiration by surviving vegetation,” and also confirm a growing body of literature that documents increased snow evaporation following tree die-off in water-limited, snow-dominated forests.
The bad news is that the loss of so many trees may not help alleviate the long-term drought in the West, as many have hoped. The good news is that researchers can use the new understanding of forest water cycles to manage healthier forests that are more resistant to drought but still supply water to agriculture and cities downstream.
Top image: An Orange County Water District worker draws a water sample produced by the district’s groundwater replenishment system, which purifies wastewater for release into the groundwater basin, on Friday, June 26, 2015. The district has expanded the system to produce 100 million gallons (379 million liters) of water a day, the largest such system in California. (Amy Taxin, Associated Press)