The Drought’s Effect on Water Quality in Southern California

California is in the throes of the worst drought it’s experienced in the last century. The focus thus far has been on water conservation, reclamation, and alternative sources—and rightfully so, given the lack of water available in the State. There is, however, another potential water issue related to the drought looming in the shadows, of less immediate concern but deserving of concern nonetheless. That issue is water quality.

In an attempt to better understand the drought’s effects on water quality in Southern California, we contacted three industry experts—Craig Miller, Deputy General Manager at Western Municipal Water District; Celeste Cantú, General Manager of the Santa Ana Watershed Project Authority (SAWPA); and Gary Lynch, retired Vice President of Water Quality at Park Water Company—and asked them to share their knowledge and perspectives on the topic.

An example of CA’s conservation efforts. Photo credit: CBS News

Certainly water quality is contingent on water quantity, which is why California public policy makers, water professionals, and residents have and are continuing to concentrate on ways to conserve and replenish the water supply.

“In this case, quantity is more crucial than quality; We need water first,” said Miller. But despite the importance of quantity, it cannot come at the expense of quality.

As Miller also explained, “The biggest priority as a retail water agency is serving high quality water that meets all of the Federal and State health requirements.”

For Western Municipal Water District and other California water agencies, the focus may be on sustaining the water supply but the end goal is always potable water for consumers. Unfortunately, the drought is placing strain on that end goal by threatening water quality.

According to Cantú, the drought is likely having a negative impact on water quality in three major areas: domestic consumption, agriculture, and wildlife.

In terms of domestic consumption, Lynch explained that potential impacts on water quality stem, in part, from lowered turnover in water mains and water storage tanks. As the water sits, particularly on hot summer days, there is greater risk of chlorine degradation and potential formation of disinfection byproducts.

“The design of water systems to meet fire flows presents the challenge of keeping water fresh to begin with,” said Lynch. “Cutting usage by 25 percent creates an even bigger challenge, operationally, to keep water fresh.”

The lack of rainfall is also problematic. “Any time you’re not getting rainfall and runoff from ambient basins, your basins are going to degrade,” explained Miller. This means that when those basins are recovered, the water extracted is of potentially poorer quality.

“This can be challenging from a political standpoint,” said Miller. “Can my ratepayers afford to clean up the water?”

Southern California receives a significant amount of its water supply from Northern California. Therefore, drought effects on Northern California—such as limited rainfall, drier conditions, and changes in inflow into the Delta—all have the potential to negatively affect water quality in Southern California. One such problem, as Miller explained, is increased level of TDS in potable drinking water, which translates into increased levels in discharges into wastewater treatment plants and increased levels in groundwater.

Another significant contributor to the Southern California water supply is the Colorado River, which is naturally salty.

“Historically we have blended down the salt with sweeter Delta water,” explained Cantú. “But the drought has affected the import of Delta water so we have more Colorado River water, which means we have less salt dilution. Over time this will be a problem.”

Salt build up is a challenge when it comes to water recycling.

Image of salt build up around crops. Photo credit: Agriculture and Natural Resources, University of California

“Every time humans touch water it gets saltier,” said Cantú. “If you’re going to follow that drop in its cycle, every time a person uses it, it becomes saltier. Every time we put it on our yards, it becomes saltier. So in what we collect—either through runoff or wastewater sewer plants—there is salt.”

Cantú explained that salt is hard to treat. The Santa Ana region has desalters which push the water through membranes and separate NaCl (salt) from H2O (water). The salt is then conveyed via a brine line to Orange County where it is treated and put it into the ocean. Unfortunately, other major Southern California counties, like Los Angeles and San Diego, don’t have these systems and, therefore, have a harder time treating salt build up.

“In terms of agriculture, salt management is a silent killer,” said Cantú. She explained that agricultural farmers used to flood irrigate their crops, which was inefficient from a conservation aspect but effective in moving the salt to below root level. Drip irrigation and limited water use do not move the salt, resulting in build up that, according to Cantú, will likely have a long-term negative impact on agricultural production because many crops are salt sensitive.

Of course, if salt is building up due to limited water use, other minerals and contaminants may be building up as well. One such likely contaminant is perchlorate, which is a legacy problem in the region having entered the groundwater from past industrial and farming practices.

The drought is also drying up lakes and rivers, creating water quality issues for the wildlife that inhabit such bodies of water. Examples include the Salton Sea and Lake Elsinore here in Southern California.

Lake Elsinore. Photo credit: Valley News

“Lake Elsinore has been managed really well and they’ve been able to keep fish kills to a minimum, but the drought poses a serious challenge for water quantity and quality for lakes,” said Cantú.

These, of course, are only a few of the challenges and potential ramifications of the drought. Despite being years into this historic drought, we are still in the early stages of understanding its full impact on water quality. This is in part because the focus is currently on water quantity, but also because it may take another few years before we begin to see more significant damage to water quality in California. As Miller explained, working toward high water quality is a continuous and steadfast process.

“From a water quality standpoint, we like to operate on a big buffer so that we have lots of time to react,” said Miller. “Being proactive about potential water quality issues is key.”

So what does the future hold for water quality in Southern California?

According to Miller we should focus on more sophisticated water recycling programs, utilization of TDS source waters further down the watershed, greater collaboration between agencies, program compensation for less expensive salt treatment, and more groundwater cleanup and use.

Lynch foresees development of more conservation-friendly strategies to preserve water quality. “The irony in a drought is that as water stagnates in the distribution system, the remedy is flushing the system to waste. This is not what we want to do nor is it what our conserving customers want to see,” explained Lynch. “Future strategies will be needed to prevent wasting of flushed water.”

In addition to focusing on water quality issues affecting domestic consumption, agriculture, and wildlife, Cantú suspects that there will likely be more investigation into the potential influence of the drought on constituents other than salt—such as perchlorate, arsenic, and hexavalent chromium—because such constituents are more harmful to human health and therefore greater threats to water quality.

While the extent to which the drought will negatively affect water quality in Southern California is still unclear, there is one known truth succinctly summarized by Cantú:

“As the drought continues—and we have every reason to believe it will—we have to make every drop go as far as possible.”

 

Special thanks to Craig Miller, Celeste Cantú, and Gary Lynch for their expertise and assistance with this piece.

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