California is recognized as one of the world’s hotspots of biodiversity, with more species of plants and animals than any other state. And a significant number of the state’s species, from frogs to birds, live in habitats that depend on groundwater.

These rich ecosystems — including spring-fed streams, wetlands, riparian forests and oak woodlands — are vulnerable to declines in groundwater levels. In areas where unchecked pumping from wells severely depletes aquifers, once-thriving wetlands and forests can dry up and die.

Spotting threats to vulnerable natural areas has become a mission for Melissa Rohde, a hydrologist who has spent years analyzing satellite data and water levels in wells to come up with strategies for preventing ecosystems from being left high and dry.

“Nature has been getting the short end of the stick. It basically gets whatever is left behind, which oftentimes is not enough,” Rohde said. “How do we ensure that these ecosystems are protected?”

California is the only state with a groundwater law that includes provisions intended to protect groundwater-dependent ecosystems. But the law, adopted in 2014, gives considerable leeway to local agencies in developing water management plans that prevent “significant and unreasonable adverse impacts.”

When Rohde and other scientists examined the local plans for parts of the state that fall under regulation, they found only about 9% of groundwater-dependent ecosystems are adequately protected, while the remaining 91% are vulnerable.

When they looked at the entire state, they determined only 1% of the ecosystems are sufficiently protected under measures adopted to date.

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Rohde has been focusing on finding ways to change that, in California and around the world.

Often working at home, she has pored over satellite data to spot decreases in vegetation greenness during drought, a telltale sign of die-off caused by declining aquifer levels. And she has analyzed how different types of trees, including willows, cottonwoods and oaks, fare when water levels fall depending on the depth of their roots.

Rohde and other researchers recently published a study outlining how California can set targets for maintaining groundwater levels — based on a formula including the type of vegetation, local water data and satellite imagery — to ensure the plants that anchor each ecosystem will be able to reach water and survive during dry times.

Cattle graze at the Kern River Preserve.

(Robert Gauthier / Los Angeles Times)

“If we don’t have groundwater levels that are able to support these diverse native vegetation ecosystems, then basically we run the risk of losing that important habitat for a lot of our threatened and endangered species,” Rohde said. “When you play around with keeping groundwater levels too deep to support the habitat, then you could lose species, and then that’s irreversible. The consequences can be severe.”

In California’s Mediterranean climate, trees, shrubs and the species they support are naturally adapted to drought. But excessive pumping from wells can push habitats beyond ecological limits by depleting the sources that sustain them.

With humanity’s heating of the planet intensifying droughts, the strains affecting these ecosystems continue to grow.

Already, California has lost the vast majority of its original wetlands to development, water diversions and agriculture. To avoid losing what remains, Rohde said, the state needs “a precautionary and preventative approach that can ensure that these ecosystems can withstand the intensification of droughts in climate change.”

During a recent visit to Kern County, Rohde and several conservation specialists walked in the shade through a lush forest of cottonwood trees near the south fork of the Kern River, visiting a nature preserve she had previously seen only in satellite images.

Scientist Melissa Rohde visits a riparian forest at the Kern River Preserve.

(Robert Gauthier / Los Angeles Times)

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At the edge of a clearing, she came upon the bare, sunbleached skeletons of dead trees.

She said satellite data had revealed that parts of the forest died along this part of the Kern River during the drought between 2012 and 2016.

“That’s because the groundwater levels rapidly declined,” Rohde said.

After that die-off, she said, groundwater levels rebounded in the area, and the native vegetation has been growing back.

The Kern River Preserve protects the riparian ecosystem along the south fork of the Kern River.

(Robert Gauthier / Los Angeles Times)

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It helps that this forest is protected as part of the Kern River Preserve, which is managed by the National Audubon Society, and that some nearby farmlands have been retired and converted to conservation lands over the years.

The preserve’s managers, working with the organization Ducks Unlimited, have also restored an expanded wetland by diverting water from the river and flooding a section of pastureland where cattle used to graze.

The wetland attracts birds, such as coots and tricolored blackbirds, and also recharges the aquifer that the roots of cottonwoods and willows tap into.

Scientist Melissa Rohde, left, and conservation specialists from Ducks Unlimited and the Audubon Society, including Reed Tollefson, right, stand on rocks overlooking a wetland at the Kern River Preserve.

(Robert Gauthier / Los Angeles Times)

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The 3,300-acre preserve has expanded as adjacent alfalfa fields have been purchased and agricultural wells have been shut down, said Reed Tollefson, the preserve’s manager. These efforts have helped protect a refuge for birds including willow flycatchers and yellow-billed cuckoos.

As he pointed to several dead trees poking from the living cottonwoods, he said protecting the forest from groundwater pumping and climate change will require additional effort.

“I think it’s tenuous,” he said. “We’ve got more work to do to try and really sustain this.”

The dead trees that have appeared here and elsewhere in California over the past decade represent the sort of die-off that water managers need to focus on preventing, Rohde said.

“It has to be an intentional practice of setting thresholds, monitoring, using satellite data or other scalable means to measure the impacts, in order to make sure that we are not allowing this to happen on a wider scale,” she said. “From a biodiversity perspective, it’s absolutely critical.”

Rohde said she felt hopeful seeing the forest rebounding and much greener than it was several years ago, with many young trees coming up.

Some other parts of California haven’t fared nearly as well.

One rainy day last month, Rohde visited an area along the Santa Clara River in Ventura County where several hundred acres of willows and cottonwoods dried up and died during the drought in the mid-2010s.

When groundwater pumping by farms and communities caused aquifer levels to fall, many trees died along the river near the city of Fillmore.

“We saw this catastrophic drop in groundwater at this site,” Rohde said.

She visited the area with a research colleague and two managers from The Nature Conservancy. They stood on a gravel road next to a lemon grove, checking on what remained of the forest.

Scientist Melissa Rohde stands in a thicket of arundo, an invasive reed that has proliferated along parts of the Santa Clara River in Ventura County. There are ongoing efforts to remove the nonnative reeds in the area.

(Brian van der Brug / Los Angeles Times)

Where native trees died, an explosion of invasive reeds has taken over. The nonnative reeds, called arundo, have grown into thickets more than 20 feet tall. And unlike willows, Rohde said, arundo offers little value as habitat for birds.

“When we had that massive die-off, and the groundwater levels remained deep, there was no way for the native vegetation to regenerate,” she said. “But arundo is extremely efficient at extracting soil moisture. And so it was able to outcompete the native vegetation.”

She said efforts to prevent this sort of habitat degradation should be prioritized.

When managers of local agencies set goals for maintaining groundwater levels, she said, they can tailor targets to the type of vegetation — whether there are cottonwood trees, with roots averaging about 9 feet long, or oaks, with roots that average nearly 30 feet but can grow much deeper.

Her colleague Michael Bliss Singer said when native trees are ravaged by multiple years of low water levels, they will start losing leaves and then dropping branches.

In one study, Singer and others documented a “brown wave” of trees drying along the Santa Clara River between 2012 and 2016 — a loss they saw in satellite images.

Scientist Michael Bliss Singer looks out over the Santa Clara River in Ventura County.

(Brian van der Brug / Los Angeles Times)

“It’s completely transformed the ecosystem here,” said Singer, a professor at Cardiff University in Wales who is also a researcher at UC Santa Barbara.

When plants die off like this and don’t recover, it’s a symptom of an ecosystem in decline. To prevent more of these losses in an era when climate change is driving more severe droughts, Singer said, it’s crucial to “come up with creative solutions for the worst-case scenario.”

Rohde has found in her research, however, that most local groundwater plans in California haven’t adequately accounted for climate projections.

Previously, Rohde did other types of climate research, including a stint in Antarctica in 2010, where she was part of a drilling team collecting ice cores. From that experience, Rohde said she realized that “I didn’t want to spend my career convincing people that climate change was an issue; I wanted to do something about it.”

She wore a faded cap with an Antarctica map, a memento of that trip. Rohde said her recent work is motivated by concerns about the climate crisis and biodiversity, as well as a conviction that proactive steps to protect ecosystems can make a difference.

“I have two young kids. I really want to make sure that I’m doing the best thing that I can to ensure a sustainable future for them, where they can access nature,” Rohde said.

E.J. Remson, a senior project director for The Nature Conservancy, surveys a wetland along the Santa Clara River in Ventura County.

(Brian van der Brug / Los Angeles Times)

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“Often groundwater is out of sight, out of mind,” she said. “We don’t measure it, we don’t understand it and we misuse it. And we need to make sure that we are managing groundwater so that it is supporting us, and making sure that we have a sustainable future.”

Rohde now works as an independent scientist. Previously, as a researcher for The Nature Conservancy, she helped write an atlas of threatened and endangered species that rely on groundwater.

California’s groundwater-dependent ecosystems lie not only along streams, but also in habitats such as mountain meadows, coastal redwood forests and mesquite bushes among desert sand dunes. The species they support range from tiger salamanders to desert pupfish, and from songbirds to mammals such as ground squirrels and bighorn sheep.

“The risks are high when species are on the verge of extinction,” Rohde said.

Rohde and other scientists have found that ecosystems sustained by groundwater are under threat worldwide. Some of the few regions that have measures intended to protect them, she said, include Australia, the European Union and California.

Still, even with California’s groundwater regulations and endangered species laws, Rohde said, “we continue to miss the mark in actually protecting them.”

Rohde said state officials should give local water agencies clear direction to ensure they’re using science-based methods to safeguard ecosystems in their state-mandated plans. She said agencies can now use the approaches scientists have outlined to map strongholds of biodiversity and set targets for maintaining aquifer levels.

“It’s very attainable,” she said. “Now, it’s just basically up to political will, or enforcement by the Department of Water Resources, to ensure that that happens.”

Walking in the rain at the Santa Clara River Preserve, Rohde followed her former Nature Conservancy colleagues Peter Dixon and E.J. Remson on a trail through a stand of healthy trees.

Peter Dixon, a project manager with The Nature Conservancy, walks on a trail through the riparian forest at the Santa Clara River Preserve.

(Brian van der Brug / Los Angeles Times)

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They stood on the banks of the fast-flowing river, watching the muddy water churn past.

In the summer and fall, this part of the river usually dwindles to a trickle.

And during the next drought, when the river dries up, the forest will depend on the same groundwater that nearby communities and farms also use.

If the water needs of this and other ecosystems aren’t prioritized, Rohde said, vital habitats will suffer.

“We need to be deliberate about the planning, and ensuring that they get their fair share,” she said. “Their existence is potentially imperiled if we don’t act.”

Having depended on hearing aids for nearly three decades, I’m astounded by the lack of Medicare coverage for devices that can solve a problem afflicting tens of millions of older Americans.

Nearly two-thirds of Americans over age 70 have some degree of hearing loss, and over half of those 75 and older experience impairment serious enough to be considered disabling. But most don’t wear hearing aids.

Because the legislation that created Medicare nearly 60 years ago specifically excluded hearing aids, those who rely on the program’s traditional coverage must pay for them out of pocket. That expense is among the chief barriers to wider use of the devices.

Age-related hearing loss impedes basic communication and the relationships that depend on it. Expanded access to hearing aids could therefore do no less than enable more older Americans to establish and maintain the social connections that are essential to a meaningful life.

Hearing loss is like an invisible, muffling curtain that falls in front of anyone speaking. Asking people to repeat themselves can yield irritated and hurtful responses. And it’s hopeless to ask a soft-spoken person to speak up. Sometimes it’s easier just to nod and smile.

Many older people I know choose to avoid social gatherings altogether because they can’t hear well. Without hearing aids, I’d stay home too.

Hearing loss can harm one’s health in other ways. For example, I’ve written about the need for a comprehensive approach to reducing cancer risk at older ages, including preventive services such as colorectal cancer screening. But these services rely on conversations between patients and their healthcare providers. An older patient’s ability to hear and understand such conversations shouldn’t be taken for granted or ignored.

The Food and Drug Administration did improve access to hearing aids by making some of them available without a prescription in 2022, but the over-the-counter devices are inadequate for serious hearing loss like mine. My private health insurance, meanwhile, started covering hearing aids a few years ago, providing up to $2,500 for them every five years. One hearing aid alone can cost that much or more, however.

Despite its limitations, my private coverage for hearing aids is better than nothing, which is what traditional Medicare provides.

Hearing loss is more common among lower-income people and those without advanced education. The toll from noisy workplaces compounds age-related hearing loss for some. One analysis found that most Americans with a serious hearing disability can’t afford the typical price of hearing aids.

Many of the older adults who can’t come up with these significant out-of-pocket expenses spent their working years in low-wage jobs that our country depends on. Denying them treatment for their hearing loss is a lousy way to treat people who gave years of service to our society.

Although some older adults with hearing loss won’t benefit from hearing aids, Medicare coverage for the devices might encourage more beneficiaries to get their hearing tested so they can get the treatment that’s right for them. And while Medicare coverage alone won’t address the stigma some people associate with hearing aids, the availability of newer, more comfortable and less obvious technology might win over some refuseniks.

Legislation reintroduced with bipartisan support last year would finally correct this glaring gap in Medicare coverage by removing the hearing aid exclusion from the law. There’s no reason to delay action on this any longer. Are our representatives listening?

Mary C. White is an adjunct professor of environmental health at Emory University’s Rollins School of Public Health, a Public Voices fellow at AcademyHealth in partnership with the OpEd Project and a former federal epidemiologist.

A second human case of bird flu in a diary worker has been confirmed in Michigan, state and federal health officials announced Wednesday.

The symptoms were mild, consisting of conjunctivitis. The Texas dairy worker who contracted the virus in March also came down with pink eye.

At a press call on Wednesday, Nirav Shah, principal deputy director of the U.S. Centers for Disease Control and Prevention, said the finding was “not unexpected” and that it was a scenario “that we had been preparing for.”

He said that since the discovery of H5N1 in dairy cattle, state and federal health officials have been closely monitoring farmworkers and slaughterhouse workers and urging farmers and farmworker organizations to “be alert, not alarmed.”

Federal officials say they still believe the human health risk of bird flu is low; however, it underscores the need for people who are interacting with infected or potentially infected farm animals or birds to take precautions, including avoiding dead animals and wearing personal protective equipment (PPE) if there’s a need to be in close contact.

Though a nasal swab from the person in Michigan tested negative for influenza, an eye swab from the patient was shipped to the CDC and tested positive for influenza A(H5N1) virus.

This is the third case of H5N1 reported in the United States. A poultry worker in Colorado was identified in 2022.

Although the symptoms in the three farmworkers in the U.S. have been mild, people elsewhere in the world have suffered more severe illness, including death. According to the World Health Organization, between Jan. 1, 2003, and March 28, 2024, there have been 888 cases of human infection from 23 countries; 463 were fatal.

In preparation for a more widespread outbreak, the CDC updated its guidance for PPE in dairies and issued a nationwide order for healthcare providers to be on the lookout for novel influenza.

On Tuesday, the CDC asked clinical laboratories and health departments to increase the number of influenza samples being analyzed “to maximize the likelihood of catching a case of H5N1 in the community,” Shah said.

The US Department of Agriculture is also expanding its surveillance and support by providing $1500 to non-infected farms to beef up biosecurity, and $100 to producers who want to buy inline samplers to test their milk. The agency will also provide $2000 per farm to cover veterinary fees for testing, as well as shipping costs to send those tests to laboratories for analysis.

There have been no cases of H5N1 detected in California’s dairy herds.

Officials said ongoing analysis of the nation’s dairy supply suggests it is safe to consume, Despite the risk to human health being low, an official with the Administration for Strategic Preparedness and Response said it will make Tamiflu available upon request “to jurisdictions that do not have their own stockpile and are responding to pre-symptomatic persons with exposure to confirmed or suspected infected birds, cattle or other animal exposures.”

Dawn O’Connell, assistant secretary of the preparedness agency, said it started the “fill and finish” process for approximately 4.8 million doses of vaccine “that is well matched to the currently circulating strain of H5N1 through the national pre-pandemic influenza vaccine stockpile program.”

She said the decision to get started on H5N1 vaccines was not a response to any heightened concern, but since it takes several months to fill and finish vaccine doses, the agency “thought it made sense given what we were seeing.”