This is Eileen Wray-McCann for Circle of Blue. And this is What’s Up with Water, your “need-to-know news” of the world’s water, made possible by support from people like you.

In Mexico, a dispute over a beverage corporation’s use of groundwater reached a turning point. Constellation Brands is a drinks conglomerate based in the United States. Its labels include the Mexican lagers Corona and Modelo. Constellation intends to build a $1.5 billion brewery in northern Mexico, in the border city of Mexicali. The brewery has drawn widespread criticism from environmentalists and locals, who say the plant could intensify water shortages in a region that is already parched. This week, Mexican president Andrés Manuel López Obrador said the government would hold a “consultation” with the public to help determine whether the brewery should be allowed to open. Lopez Obrador did not go into detail about the consultation process, according to Reuters news service, but U.S. officials said they oppose the idea. Constellation said it would consider locations outside of Mexico if the brewery project is held up by the consultation.

In the United States, a new study finds that crops grown for cattle feed are the largest consumers of river water in the American West. Crops like alfalfa and corn demand more water than power plants, cities, and industries, according to the study, which appears in the journal Nature Sustainability. And the pressure is especially severe in the drying Colorado River basin. While in general, cattle-feed crops account for a third of all river water consumption in the American West, the figure in the Colorado River basin is much higher, with 55% of river usage going to feed crops, according to the recently published research. Brian Richter is the lead author for the study. He says that even though irrigation places significant stress on river ecosystems, there is an option. Richter says that farmers should be paid not to irrigate. Instead of growing crops, they would let some fields lie fallow to leave more water in rivers, where it can support over five dozen threatened fish species in the western states.

In Michigan, the legal battle stemming from the Flint water crisis continues to play out in court. Last week, the state Supreme Court heard arguments over whether Flint residents should be able to sue state officials for their role in the city’s lead crisis. A switch in the city’s source water in 2014 caused pipes to corrode, which released lead into drinking water. In addition to a spike in lead levels, at least a dozen people died in a Legionnaires’ disease outbreak that was linked to degraded water quality. The state appeals court ruled in 2018 that residents had the right to sue over violations of their “bodily integrity.” The Michigan attorney general’s office is appealing that decision. The case hinges on whether public officials violated the state constitution during the water crisis.

This week, Circle of Blue reports on a neglected flood risk in California.

On a calm, sunny day at the start of a rainless February in the San Francisco Bay Area, streets are flooded. The cause is a complex and concerning relationship between climate and hydrology.

The Manzanita area of Marin County floods more than 30 times a year, even on blue-sky days. The flooding is the work of king tides. They are the biggest tides of the year, and they lifted water levels in San Francisco Bay to annual highs in the first week of February. King tides are worse in the winter, and they offer a climate change preview, a glimpse of what average water levels could be decades in the future.

But king tides are only part of the region’s flood story. As sea levels rise, so do the waters in the bay, which connects to the Pacific Ocean through the Golden Gate. The relationship between rising ocean levels and rising bay levels is well known. What is less obvious is that groundwater levels are rising as well, adding another variable to the region’s equation of increasing flood risk.

Kristina Hill is a professor at the University of California, Berkeley, who studies urban design and flooding. She’s been instrumental in shedding light on this neglected aspect of flood risk in the Bay Area. The rise in groundwater adds to flooding in low-lying communities in the nine counties that ring San Francisco Bay. Even before it comes to the surface, rising groundwater takes its toll. It infiltrates sewer pipes, which can cause backups and burden treatment plants with excess water. It destabilizes building foundations, corrodes pipes, and could dislodge pollutants caught in soil particles, setting the toxic substances free in the environment. Hill said that groundwater is the unexplored angle in a “trifecta” of flood risk factors that includes rains and tides. She told Circle of Blue: “You get a high tide, you get a rainstorm and you get this higher groundwater, and the flooding gets worse all the time.”

Preparing for such threats could be enormously expensive. An earlier assessment found that defending Bay Area shorelines from a 6-foot rise in sea-level and a flood with a one percent chance of occurring could cost $450 billion. Hill’s team used data from more than 10,000 State Water Board wells to create a map. They found that a huge area of bay shore is already within three feet of the water table in a wet year. Rising bay levels would bring that water even closer to the surface, according to their research, published last October in the journal Water. If the sea level rose about three feet with no additional walls or levees, some 28 square miles of land in the Bay Area would be inundated from water coming from the bay. This overland flooding, as it turns out, is the smaller share. The analysis found that an additional 40 square miles of land would be flooded by rising groundwater levels.

For those familiar with California’s highly publicized struggle against groundwater depletion, the results of the study could be confusing. Hill is careful to point out that not all regions face the same problems. In the Central Valley, Salinas Valley, and other farming regions in California, the overriding concern is too little groundwater. Groundwater in those places is deeper and is disappearing. In the Bay Area, by contrast, groundwater is shallow, influenced by rainfall and tides, and generally not used for drinking. For manmade structures, it is more harmful than helpful.

Hill’s groundwater map showed potential flooding hotspots in numerous Bay Area communities: Alameda, Marin City, Redwood City, San Rafael, Tam Valley, and around Lake Merritt in Oakland. Many developments in these areas are built atop former wetlands that were filled in. Draining water from these places can cause subsidence, or sinking of the land surface, a process that also magnifies flood risk. That means that pumping, a favored solution of engineers, is not an easy option for mitigating floods in these locations.

Current flood risk maps in the Bay Area are inadequate and underestimate flood risks. The maps do not incorporate groundwater-related flooding or subsidence when looking at future sea-level rise. Hill warns that ignorance of groundwater-related flooding could dramatically undermine California’s response to rising waters in the bay. Larger sea walls and levees will not keep out rising groundwater.

And that’s What’s Up With Water from Circle of Blue, which depends on your support for independent water news and analysis. Please visit and make a difference through your tax-deductible donation.