Nevada Wildlife Advocates Say Rare Toad May be Harmed by Geothermal Plant
U.S. Route 50 across Nevada has been called the “loneliest road in America.” But if you hang a turn onto Nevada State Route 121 North, then follow it until you run out of pavement, you’ll be a whole lot lonelier than anyone on U.S. 50. The blacktop ends four hundred miles north of Las Vegas, between northern Nevada’s Stillwater and Clan Alpine mountain ranges, in a bit of Great Basin desert called the Dixie Valley. There used to be a small settlement here, but the U.S. Navy bought everyone out a couple of decades ago so that it could expand its “Topgun” training at the nearby Fallon Naval Air Station.
The Dixie Valley is notable for a few things other than solitude. One is the fires of hell a few feet below the surface. The Dixie Valley has hot springs, some of them hot enough to cause third-degree burns in less than a second. It has fumaroles — vents through which superheated steam escapes the earth and humidifies the local desert. It has a geothermal plant at its north end, which turns the hot groundwater into electrical power for Southern California Edison.
The Dixie Valley also has a salt marsh, one of just two in the whole state. The Humboldt Salt Marsh, about 10,000 acres in extent, occupies the lowest-lying portions of the Dixie Valley Playa, where all the valley’s salts concentrate. Unlike coastal salt marshes, the Humboldt Salt Marsh might better be called a “brine marsh.” It’s far too salty to support plant life.
Uphill from the salt marsh, on land administered in patchwork fashion by the Navy and the Bureau of Land Management, lies a less-saline wetland called the Dixie Meadows, less than a thousand acres of desert marsh plants like three-square bulrush, watered by a constellation of springs, both hot and cold, known collectively as the Dixie Meadows Spring Complex. In among those bulrushes is the most notable thing of all about the Dixie Valley, one of the last things you’d think to find in this harsh environment: the Dixie Valley toad.
The hot springs uphill are both boon and bane to the toads. Toads that wander too close to the hottest of the springs risk death by scalding. (The hottest of the Dixie Meadows Springs has been measured at 182°F.)
Fortunately, the old saw about frogs fatally remaining in gradually heated water has no basis in fact: they hop out of the water when it gets a mite uncomfortable. It’s an unwary toad indeed who falls victim to overcooking. And a constant flow of heated water comes in handy in this cold desert valley in Northern Nevada, where sub-freezing nights are a regular feature of winter. Hot springs may well help the toads arise from hibernation earlier in the year, promoting earlier plant growth and subsequent attraction of the toads’ invertebrate prey.
Until recently, the Dixie Valley toad was assumed to be just a generally smaller version of the far more widespread western toad. (Dixie Valley toads tend to max out at around two inches “snout to vent,” while western toads can grow to more than twice that length.) Pointing to recent genetic research, some University of Nevada Reno biologists suggest the toad might be a new species. Other biologists aren’t sold on the idea. But there’s general agreement among conservation biologists that whether the Dixie Valley toad is a distinct species, a subspecies, or just a notable local variant of the western toad, it’s unique among amphibians and worthy of protection. The Nevada Division of Wildlife and the U.S. Fish and Wildlife Service have been working together since 2008 to determine how best to protect the toad.
That’s important. The Dixie Valley toad may be facing a new threat from those boiling hot springs: a geothermal energy company wants to tap the aquifer beneath them for steam power.
The Nevada-based energy firm Ormat Technologies is proposing to build one or two geothermal power plants just uphill from Dixie Meadows. The company maintains that its project, which would generate a maximum of 60 megawatts of electrical power if both plants are constructued, can be built without threatening the Dixie Valley toad’s existence.
That’s despite the fact that the proposed plant would be a massive intervention into the valley’s hydrology. It’s also despite plans to build a “gen-tie” power line across the northernmost part of the Dixie Meadows to get the plant’s electricity to market.
The main reason Ormat expresses confidence that its operations won’t hurt the toad is that on paper, the plants’ net water consumption will be fairly low. Geothermal energy generation involves using very large amounts of water, tapping it as superheated water in a geothermal aquifer and using it to power steam turbines at ground level.
But water’s in extremely short supply in the desert. Ormat’s plant will be using more than 20,000 acre-feet to generate power each year. (That’s about the same volume of water as Glendale, California uses in the same time period.) Pumping that much water and letting it vaporize in the desert air would dry up the Dixie Valley aquifer pretty fast. So in Dixie Valley, Ormat would pump that water back into the aquifer. Instead of using that geothermal water to maintain temperature in “wet-cooled” steam turbines, Ormat would use airflow to discharge excess heat from the plants’ “dry-cooled” turbines.
Ormat thus claims its plants will have minimal potential impact on the Dixie Meadows Springs.
The project’s federal Environmental Assessment echoes Ormat’s contention that groundwater won’t be affected:
“If the project were to consume geothermal fluid during operation geothermal reservoir pressures could fall. This could alter water quantity by reducing spring flows or water levels of groundwater aquifers that may have a hydrologic connection to the geothermal reservoir. If water from the basin-fill aquifer were injected into the geothermal reservoir to maintain suitable production pressures … the same impacts could result on springs or overlying groundwater aquifers. However, operating the air-cooled geothermal plants is not anticipated to consume geothermal water resources, as all geothermal fluid used in production would be reinjected back into the geothermal reservoir.”
Nevada environmentalists aren’t so confident the plant won’t drain the swamp.
“It seems highly unlikely that one could pump and reinject 23,000 acre feet of water per year without having any effect whatsoever on the surface expression of that water at the springs,” says Patrick Donnelly, Nevada Wildlife Advocate with the Center for Biological Diversity. “Ormat has provided zero evidence to back up their claims that they would not impact the springs. Nor have they provided a plan for how they would measure any potential impacts, and how they might mitigate such impacts.”
Donnelly (who, in the interests of full disclosure, has been my friend for some years) points out that overdrafting of an aquifer is often well underway before any changes are seen in springs at the surface.
“Let’s envision a scenario in which Ormat detects that there are declines in spring flow at Dixie Meadows,” he says. “Even if their chosen mitigation for this would be to cease operations altogether (which seems unlikely after a multi-million-dollar investment in construction), it could take years or decades for water levels at the spring to recover. Should the springs dry out completely, even just for a short period of time, it would spell doom for the Dixie Valley Toad.”
Paul Thomsen, Ormat’s Executive Director for Government and Regulatory Affairs, says his company wants to do everything it can to keep that from happening. “Ormat is committed to building the Dixie Valley project in the most environmentally friendly way possible,” Thomsen told me. “We will meet any environmental requirements placed on this project by the Bureau of Land Management. We look forward to meeting those requirements.”
Some of the potential mitigating strategies promised in the project’s Environmental Assessment include exclusion fencing to keep toads out of project areas, maintaining a buffer between the construction site and toad habitat, keeping construction areas out of the wetlands, and “adaptive management and reporting” of groundwater conditions to “ensure a no net loss of special status species and habitats.” The toad chief among those special status species.
“We will meet any environmental requirements placed on this project by the Bureau of Land Management. We look forward to meeting those requirements.Paul Thomsen, Ormat Technologies
Despite the company’s assurances, there may be some reason for concern over the effect even a closed-loop, dry-cooled geothermal power plant might have on nearby springs.
One of Ormat’s nearby projects provides an example. The company’s 10-megawatt Jersey Valley Geothermal Project, 42 miles northeast of the proposed Dixie Valley project, began operation in 2011. In 2009, the nearby Jersey Hot Spring had been flowing copiously, by desert standards, at about 50 gallons per minute. But that spring started slowing when the Jersey Valley power plant went online. By May, 2013 the spring’s flow had dropped by half, and in August 2014 — the last time the spring level was surveyed, according to the Nevada Division of Water Resources — the water at Jersey Hot Spring had stopped flowing.
There are other reasons Jersey Hot Spring might have dried up, including the Southwest’s multi-year drought in full swing in 2014. (Though in August 2009, after several years of drought, flow at Jersey Hot Spring was holding steady at more than 40 gallons per minute.)
“A closed-loop geothermal system went online, not consuming water and thus ostensibly not impacting surface water resources, and an adjacent spring went dry,” says Donnelly. “While we don’t have a direct causal link, the correlation is awfully suspicious.”
Due to the pending holiday, I was unable to speak with Bureau of Land Management staff familiar with the Jersey Valley power plant and hot spring by press time. (Again, I’ll update this story as necessary.)
Tapping the Dixie Valley’s groundwater is the greatest potential threat from the geothermal plant, but the plant footprint itself also poses some potential dangers, from the possibility of toads being injured during construction to changes in the Meadows as rainstorms run off the plant’s hard surfaces, potentially cutting arroyos through the wetland. There's also the potential for substances released from the geothermal aquifer, such as the highly toxic hydrogen sulfide, to harm the toads and their habitat.
And while Donnelly says he saw startling numbers of toads on a recent visit — “I would even use the word teeming; Dixie Meadows is teeming with Dixie Valley toads,” he told me — the amphibian is nonetheless restricted to around 400 acres of habitat, living nowhere else in the world. Even a short drought in the meadow could conceivably push the Dixie Valley toad into extinction.
The Center for Biological Diversity is encouraging members of the public to comment on the project’s Environmental Assessment by the end of Friday, June 30, asking commenters to endorse the “no action” alternative, under which the project would not be built. The group will also be pursuing emergency listing of the Dixie Valley toad as an Endangered species under the U.S. Endangered Species Act.
"The Dixie Valley Toad is staring extinction right in the face," says Donnelly. "We will use all of the tools at our disposal to prevent that from happening."
Banner: Dixie Meadows | Photo: Patrick Donnelly