From The High Country News (Emily Benson):

Upstream mining has left a toxic legacy at the bottom of Coeur d’Alene Lake.

Early this spring, a migrating flock of tundra swans flew toward a long and narrow body of water in North Idaho marked on today’s maps as Coeur d’Alene Lake, seeking a stopover on their way north.

From a few thousand feet, the birds would have seen the expanse of the lake, surrounded by forested hills and shaped roughly like a human arm. Near the elbow, they would have flown over the political boundary marking the edge of the Coeur d’Alene Tribe’s reservation, which encompasses the southern third of the lake. To the north, the swans, thousands of them, would have glimpsed the high-rises of the resort town of Coeur d’Alene at the lake’s edge, and the lake’s outlet, the Spokane River, winding west. They would have passed sandy beaches and rocky peninsulas dotted with marinas, parks, homes and resorts, and the Coeur d’Alene River, which meets the lake at Harrison Slough. It is an appealing place to alight — and a lethally toxic wetland.

Indeed, many of the swans stopped at the slough. There, they stretched their long necks under the water, digging into contaminated sediment with their beaks to root up edible plants and invertebrates. And then, just as dozens of tundra swans do every year, many of them died, poisoned by the lead and other heavy metals in the mud, a legacy of Idaho’s hard rock mining.

As attractive as it appears, the landscape around Coeur d’Alene Lake can be lethal to animals, and dangerous to humans. The local health district warns people who swim, boat and barbecue along the picturesque lower Coeur d’Alene River to brush dirt from their pets, shoes and camping gear, so they don’t track lead-laced dust into their homes.

But the area’s mining past has left an additional, and largely invisible, legacy. Far below the surface of the lake lies another threat: 75 million metric tons of contaminated sediment, lining most of the lakebed. While the pollution in the watershed is the focus of a massive and ongoing cleanup led by the Environmental Protection Agency, protecting the health of the lake itself has been left to the state of Idaho and the Coeur d’Alene Tribe. The flaws of that approach — exacerbated by mistrust, political calculations and disagreements over cleanup obligations — are now imperiling both the lake and the life that depends on it, human and nonhuman alike.

RIGHT NOW, LEAD, MERCURY, ARSENIC and other toxins are bound up in the bed of Coeur d’Alene Lake. That contamination is sequestered there and stays relatively dormant, owing to the chemical conditions of the water. But scientists monitoring the lake say all this could change as more nutrients filter in from the watershed. They’re already seeing rising nutrient levels in some areas. That could one day trigger a release of contaminants into the lake, at poisonous concentrations.

The science is complex, but critical: The toxins are lodged in the lake’s sediment by a twist of chemistry, kept in check by the oxygen in the water. However, if the layer of water above the sediment loses all of its oxygen, the chemistry changes. If there’s an algae bloom, for instance, which nutrient pollution can cause, then Coeur d’Alene Lake is in trouble. When algae die, they sink to the bottom of the lake and decompose, in a process that can consume all the oxygen there. The resulting toxic cascade would devastate the lake’s ecosystem, starting with the algae. They could turn the clear, inviting lake into a vat of pea soup, the kind of mess that, in other places, has shut down water supplies and caused fish die-offs.

The region’s human inhabitants rely on the lake. It supports both a bustling recreation industry and significant lakeside property values, which would be threatened by algae blooms and toxin releases. The lake’s outlet, the Spokane River, is a major supplier of water to the Spokane Valley-Rathdrum Prairie Aquifer, the source of drinking water for more than 500,000 people. And culturally, the value of Coeur d’Alene Lake is unquantifiable; it’s considered a gem by the people of North Idaho, and its potential loss is so devastating as to be almost inconceivable.

Unfortunately, phosphorous nutrient levels have been increasing lately in the northern part of Coeur d’Alene Lake, with last year’s some of the highest on record. If regulators can’t rein in those nutrient inputs, major algae blooms and a massive release of lead and other toxic metals could result.

THE TOXIC CHEMISTRY is a large part of the problem the lake is facing. But there’s also a toxic history at work in the watershed.

The traditional homeland of the Coeur d’Alene Tribe extends across about 5 million acres of what is now western Montana, the Idaho Panhandle and eastern Washington, centered on Coeur d’Alene Lake. The people who lived there caught fish, harvested an aquatic root called the water potato and traveled along the lake and its rivers. They also pondered the lake and its origins and told stories about it, as they still do today.

By the mid-1800s, white missionaries, traders and soldiers were common visitors to the area. In the early 1870s, the Coeur d’Alene Tribe and the U.S. government negotiated the boundaries of a reservation that included — at the tribe’s insistence — nearly all of Coeur d’Alene Lake. But the U.S. Congress never ratified it. Instead, in 1890, it finally approved a significantly reduced reservation, which encompassed only the southern third of the lake.

Meanwhile, mining in the region was ramping up. In 1884, two brothers staked a claim on a tributary to the South Fork of the Coeur d’Alene River, upstream of the lake. By the end of the 20th century, that mine — one of dozens in what’s called the Silver Valley — was the most productive silver mine in the world. From the 1880s onward, companies like now-closed Bunker Hill, the region’s largest mining company, extracted millions of tons of lead, zinc and silver from the area. And millions of tons of toxic waste have been left behind, blown onto Silver Valley hillsides by smoke stacks employed during ore processing, discarded in tailings piles strewn across the floodplain, and washed downstream to Coeur d’Alene Lake.

In 1983, the federal government added the area to the list of Superfund sites, the most severely contaminated hazardous waste dumps in the country; one of the first, and perhaps most famous, was Love Canal, in New York. Overseen by the Environmental Protection Agency, the program cleans up contamination with money that comes primarily from annual appropriations by Congress and the companies responsible for the pollution; states are responsible for covering at least 10% of the cost. In the Silver Valley, the agency’s early efforts addressed human health risks in small towns like Kellogg, Pinehurst and Smelterville, Idaho, through initiatives like replacing the soil of contaminated yards and playgrounds with clean dirt.

During the same period, in 1991, the Coeur d’Alene Tribe sued the state of Idaho, embarking on a decade-long legal battle to affirm its ownership of Coeur d’Alene Lake. That fight culminated in a 2001 U.S. Supreme Court decision ruling that “the bed and banks” of the southern third of the lake belong to the tribe. Idaho controls the rest. The two governments were yoked together as joint managers of the lake.

Upstream, the cleanup was working. By 2002, lead levels in the blood of Silver Valley residents were low enough to meet the EPA’s goals, and the agency had shifted its focus to include the rest of the Coeur d’Alene Basin, including Coeur d’Alene Lake. The same year, the agency released a “record of decision” — essentially a cleanup plan — to address contamination outside the Silver Valley.

That plan is important. It now guides how the EPA spends Superfund dollars in the Coeur d’Alene Basin — a total of nearly $700 million earmarked for cleanup in 2011, after major settlements with mining companies ASARCO and Hecla. The plan called for a range of activities, including treating wells and capping contaminated areas. But following a whirlwind of fierce local and state opposition to the perceived stigma of a Superfund label, the plan did not touch the toxic sediment at the bottom of Coeur d’Alene Lake.

In other words, though the lake was — and still is — part of the Superfund site, the 2002 decision carved it out of the area where Superfund money could be spent. Instead, the EPA developed an alternative: It helped broker a plan between Idaho and the Coeur d’Alene Tribe to manage lake contamination outside of the Superfund program.

But that framework, called the 2009 Lake Management Plan, has never been well-funded, and it lacks the regulatory teeth to prompt substantial change. Two and a half years ago, the Coeur d’Alene Tribe’s scientists raised an alarm over declining oxygen levels and rising signs of algae in Coeur d’Alene Lake. Now, as cooperation on the plan crumbles, the future of the lake — and of those who rely on it — is in peril.

REGARDLESS OF THE SETBACKS, efforts to understand the lake and avert a calamity continue.

On a clear morning last October [2018], the tribe’s lake scientists invited me out on their boat to see how they monitor water quality in Coeur d’Alene Lake. The day started off chilly and bright, the kind that seems to want to hold onto summer even as the coming winter looms. Despite the sunlight sparkling across the tops of the wavelets, it was cold on the water. We huddled in the boat’s heated cabin as we sped away from the marina, the roar of the twin engines insulating us from the world outside.

We stopped at a site the researchers call C5, partway up the forearm of the arm-shaped lake. Despite the chill, Dale Chess, a research scientist for the tribe, wore sneakers and shorts on the boat’s back deck as he gathered ropes, buckets and a Hydrolab, a high-tech device that can measure water temperature, dissolved oxygen and other parameters. Inside, Michael George, a technician and a member of the Coeur d’Alene Tribe, and Scott Fields, a program manager for the tribe’s Lake Management Department, transformed the boat into a floating laboratory, preparing sample bottles and a water filtering station.

According to U.S. Geological Survey data, in recent years, 98% of the lead that flowed into Coeur d’Alene Lake stayed there, an average of about 480 tons per year. The rest ended up somewhere downstream of the lake. The most polluted parts of the lake are at the mouth of the Coeur d’Alene River — south of the lake’s elbow — and north of C5.

Chess explained the lake’s ecology to me as he worked. He lowered the Hydrolab into the water, carefully dropping the instrument exactly one meter between readings. A waterproof cable snaked into the heated cabin, where it connected to a laptop manned by George. “How’s that depth?” Chess called to him, ready to adjust by an inch or two if needed. “That’s good,” George said.

A breeze from the south ruffled the water, sloshing rhythmic waves into the metal pontoons of the boat. In churning it, the wind also helped mix oxygen from the air into the lake, but only the top layer of it. Many lakes form layers of different temperatures in the summer, like a cake: As the sun warms the upper layer, the colder, denser water gets trapped at the bottom.

During the summer, the top layer seals off the bottom, preventing oxygen from reaching the lower layers. That means there’s only a finite amount of oxygen available at the lake bottom until the fall, when the upper layers cool off enough that the whole lake mixes again. At C5, the oxygen is almost gone by the end of the summer. Because of that, it’s an important area to keep an eye on. If regulators pay attention to the scientists, this could be an early-warning sign before catastrophic toxins are released from the lakebed. “It’s the site that’s really going to respond first,” Chess said. “We call it the canary in the coal mine.”

Laura Laumatia, at the time the Lake Management Plan coordinator for the Coeur d’Alene Tribe, was out on the boat, too. A sunny woman with blond hair, she stood on the front deck at our next stop, in the southern, less-polluted section of the lake. She flung a hoop with fine mesh tied to it, like a butterfly net without a handle, over the side, then reeled it in and pulled it, dripping, back into the boat. Unscrewing the small plastic container at its base, she dumped the contents — greenish water, alive with hundreds of tiny, swimming organisms, each the size of a grain of salt — into a white five-gallon bucket. The bucket was destined for a classroom in Wallace, Idaho, where the teacher planned to use its contents to illustrate a lesson on food webs, hoping to help students understand that nothing lives in isolation.

Much of the problem with the Lake Management Plan, Laumatia had explained to me, is that it lacks regulatory authority. It includes goals like monitoring the lake, public outreach and identifying nutrient inputs, but no tools for enforcing reductions. Nutrients flow into the lake from a variety of sources, including diffuse ones like agricultural runoff and erosion from forests; specific ones like wastewater treatment plants; and also things individual communities or homeowners have more control over, like stormwater, lawn fertilizer and septic systems. But the plan doesn’t give the tribe or the state agency that’s party to it — the Idaho Department of Environmental Quality — direct power to limit pollution. Instead, policies and actions to rein in nutrients are largely left up to local governments and members of the public. So outreach and education were a big part of Laumatia’s job. If residents of the watershed understand the problem and the threats, they might, for example, welcome land use regulations that would keep nutrients out of the lake.

But that can be a tough idea to sell in North Idaho, where regulations are often seen as an infringement on private property rights, and where some residents believe the lake has already been cleaned up. Laumatia told me about a time a year or two ago, when she was invited to speak to the members of an influential Coeur d’Alene Lake property owners’ association. As the group’s leader was introducing her, he called the core logic of the Lake Management Plan itself — the idea that changing chemical conditions could release metals from the lakebed — a myth. “To be introduced in that way was so disheartening,” Laumatia said. The problem wasn’t that people disagreed on solutions, but that “there are individuals that are questioning the very idea that something needs to happen at all.”

After we finished collecting samples and measurements, we motored a few hundred yards up the St. Joe River, Coeur d’Alene Lake’s other main tributary, looking for the two moose we’d heard were hanging out there. Sure enough, we spooked them, a cow and small bull on the levee by the river’s outlet. As the animals ran across the spit of land, the cow loped through a thicket of cattails, launching a whirlwind of fuzz a dozen feet into the air, where it hung, floating in the sun.

SUCH VIBRANT LIFE ON THE LAKESHORE belies the dearth of living things below the surface, thanks to another toxic metal left over from mining — zinc. Zinc creates yet another conundrum for the lake and those who rely on it. Thirty-five percent of the zinc that enters the lake, or about 150 tons, sticks around annually, with the rest flowing down the Spokane River. “It’s a contaminant that is toxic to plants and animals,” Sheryl Bilbrey, the director of the Environmental Protection Agency’s Superfund program for the region that includes Idaho, told me. “Zinc is a problem in the system that we need to remove.”

To do that, the federal government is paying $48 million to upgrade a water treatment plant and build a groundwater collection system near Kellogg. Once the renovations come online in 2021, the facility, called the Central Treatment Plant, will strip zinc from groundwater contaminated by mining waste before it’s released downstream.

But there’s a catch: Because zinc is toxic to aquatic life, it may be keeping plants and algae in Coeur d’Alene Lake in check — like the chlorine that keeps a swimming pool clear. Remove it, and we don’t really know what will happen, though many scientists are concerned that if enough zinc is taken out of the system, algae growth could spike and release the toxic metals at the lake’s bottom. (The EPA disagrees that the upgrade will be an issue. “We certainly don’t want to create a problem in the lake, and we don’t think we are,” Bilbrey told me.)

“We want to meet water-quality standards, we want to have low metals, we want our lake to be healthy,” Craig Cooper, a lake scientist for the Idaho Department of Environmental Quality, told me. “So, getting these metals down is a good thing. But … it also exposes us greater to risks they were suppressing.”

Layered on top of that challenge are additional stressors, Cooper said, like climate change. Take, for example, the increased wildfire in the West. Wildfire soot and ash, which contain nutrients like nitrogen and phosphorous, can settle or get washed into rivers and lakes, especially when runoff surges after a blaze. More fires across the region could mean even more nutrients coming into Coeur d’Alene Lake. “We’ve got to pay attention to (controlling nutrients), we can’t just paper it over,” Cooper said. “We’re working on it … (but) there’s more we can and need to do, because if we don’t, then we lose this irreplaceable, priceless gem.”

POLITICAL BOUNDARIES DON’T MIRROR the natural edges of watersheds. And that means reducing nutrients to protect Coeur d’Alene Lake requires cooperation between agencies and governments with long, complex histories.

There are examples of successful collaborative projects in the watershed. For instance, Caj Matheson, a member of the Coeur d’Alene Tribe and the director of its natural resources department, told me about a partnership among the tribe, the state and a local children’s camp to rebuild a buffer at the edge of the camp’s property, thereby preventing nutrients from running into the lake.

To some extent, cooperation depends on the relationships individuals build, regardless of the history between the groups they’re affiliated with. Still, differences in values drive tensions that are difficult to overcome. It often boils down to concerns over individual rights versus a community outlook, Matheson told me. “Folks on one side don’t necessarily trust other people to do what’s right for everybody and for the environment, and on the other side I think people don’t trust that there’s enough respect for their personal private property,” he said. He also pointed out that many private property owners in the basin are willing to do what’s best for the lake. But, he said, “It’s hard to build the trust, easy to shatter.”

Many lakes across the country host lake associations, groups of people who own property along the shoreline. These can operate as social clubs and fundraising bodies, and often include an aspect of environmental conservation. The Coeur d’Alene Lakeshore Property Owners Association, however, appears to be largely dedicated to protecting its members’ private property rights. As a 2018 newsletter for the association notes: “CLPOA continues to fight for the issues that protect our right to use our waterfront property without unnecessary regulation and restrictions.”

Those issues include the Coeur d’Alene Tribe’s water rights claims, which the association is legally challenging as part of a lengthy adjudication process overseen by the state. Idaho sees that fight as separate from disagreements over the Lake Management Plan, since different agencies govern each process. But the tribe doesn’t compartmentalize things that way. “We govern things and manage things in a more holistic sense,” Matheson told me. “We see, on one hand, the state of Idaho doing this, but on the other hand, the state of Idaho doing that,” he said. “It makes it really, really tough for us to trust the state.” But with the future of the lake at stake, “whether you trust or don’t trust, the bottom line is … we’re all still working on it together, because we have to.”

IN APRIL [2019], I attended an environmental conference in Spokane, hosted by the Spokane River Forum. Outside, damp air rose from the river, the roar of its falls mingling with the rumble of traffic zooming over a bridge. Inside, a few hundred people — scientists, students, agency employees, resource managers, local officials and others — gathered to discuss issues concerning the Spokane River-Coeur d’Alene Lake Basin.

There, I met with Phillip Cernera, the director of the tribe’s Lake Management Department, and his colleague, Rebecca Stevens, who sat with me at the edge of a mostly empty hotel ballroom. Our talk turned to the death toll of the tundra swans at Harrison Slough, and Stevens unfolded a large map onto the table in front of us. “Nothing’s going to happen until that stuff is happening right here,” Cernera told me, jabbing his finger at the map: the northern edge of the lake, where the buildings of downtown Coeur d’Alene are clustered near a waterfront town park. “If there were 400 dead birds washing up on City Beach, there would be an uproar.”

But no such thing has yet happened, and so the uproars tend to be about management. Two years ago, the Coeur d’Alene Tribe and the Idaho Department of Environmental Quality reported that, as of 2015, water-quality benchmarks set in the Lake Management Plan weren’t being met. At some sites, phosphorous was too high, oxygen too low and chlorophyll, a sign of algae, was rising, meaning the lake was tipping dangerously close to an outcome nobody wants. Since then, oxygen and chlorophyll measurements have improved, though phosphorous is still above the target level in the northern part of the lake.

Still, under the Lake Management Plan, the 2015 numbers should have triggered a review of the causes and prompted a coordinated plan to address them. According to the tribe, that never happened. “Since 2016, the Tribe has asked EPA and the State of Idaho what response actions will be taken,” the tribe’s lake management department staff wrote in a recent review of the plan. “Yet for more than two years there has been no response other than both agencies/governments wanting to engage in dialog to discuss the results of the water quality monitoring; that data has been available to EPA for years.”

At the Spokane environmental conference, Cernera, who, at 60 years old, has worked for the tribe for nearly half his life, stood at the front of the ballroom, where all of the attendees were gathered for lunch. He explained that, from the tribe’s perspective, the plan isn’t working: Despite its existence, the lake is deteriorating. “I really want to urge people to recognize that our lake is not some static thing; it is alive, it’s dynamic, and it’s on the decline,” Cernera said, his voice strident with emotion. “We need to protect this lake, and we’re at a crossroad. What’s it going to be?”

The tribe formally withdrew its support for the Lake Management Plan in early April, saying that the plan “has been ineffective in protecting lake water quality,” according to a letter signed by Chairman Ernest Stensgar and sent to state and federal officials. The letter goes on to ask the Environmental Protection Agency to “formally evaluate how they will use their authorities to address the legacy mining pollution that exists in Coeur d’Alene Lake.” In other words, what will the agency do now that its ad hoc alternative to a Superfund cleanup for the lake has failed to protect the waterbody? In retracting its support for the lake management plan, the tribe may force the agency’s hand — though, from the agency’s perspective, there’s nothing to force. “It’s really more of a local ordinance issue,” the EPA’s Sheryl Bilbrey told me. “There’s just a whole host of sources (of nutrients) that we don’t have authority to regulate.”

Cernera also spoke about what he’d like to see happen: An influx of funding from the Environmental Protection Agency to deal with the toxic pollution at the bottom of the lake. “Call a spade a spade,” he said. “The way I see it now, EPA is using the lake bottom as the largest repository (of mining contamination) in our basin, if not the country.”

But according to the EPA, the rules governing how it spends Superfund dollars prohibit the agency from using the money to manage the lake itself. After Cernera spoke — and the applause for him, mingled with a few whoops from the audience, had died down — representatives from the EPA and the Idaho Department of Environmental Quality also addressed the crowd.

Speaking on behalf of the EPA, Bilbrey leaned into the microphone on the table in front of her and kept her remarks brief and official. More needs to be done to protect the lake, she said, but exactly what that action might be is still the question. “The bottom line is the federal government can’t come in and tell the locals how to regulate.”

Dan Redline, the Coeur d’Alene region administrator for the Idaho Department of Environmental Quality, spoke next. He reiterated the state’s support of the Lake Management Plan, but wondered whether more was needed. “Is the Lake Management Plan really enough, given all the stresses in this watershed and where it’s going?” he asked. “I guess I’ll leave it at that.”

After Redline’s presentation, an audience member suggested some ways to reduce those stresses, like mandating the use of composting toilets and gray-water systems on shoreline properties. Why isn’t it possible, he asked, to institute those kinds of restrictions?

In response, Redline pointed to the political environment in the region. Indeed, Kootenai County, one of the three Idaho counties within the watershed, decided last year to give some homeowners the ability to opt out of building codes altogether. But even in North Idaho, politics don’t always play out in expected ways. As I later learned, the two commissioners who championed that change weren’t re-elected, and, a few months ago, Kootenai County reinstated the codes. Reading about the reversal, I wondered if there might be more support for regulations — small, sensible ones that would clearly benefit Coeur d’Alene Lake — than some might assume.

Later that day, I met a conference attendee named James “Trey” George III. He grew up in the area, moved away for a while after college, then returned and went to work for the city of Spokane last year. I asked him what he made of the panel. The contrasts between the various speakers’ remarks highlighted the quagmire they, and by extension, the lake, have found themselves in, he told me. “They all acknowledge there’s a problem. How do they solve it, and who’s got the authority?” George said. He told me about snowboarding at the ski resorts in the Silver Valley as a young adult, in the early 1990s. The landscape was so scarred by pollution that there weren’t any trees there then; now, the mountains are full of them. Perhaps that kind of change, in reverse, is the only thing that will prod Idahoans to act. “If that lake starts to go south visually, everything will change,” George said. “I have faith that if we get close to that, that we’ll reel it back in, because we don’t want to lose that lake.”

I wanted to agree, but seeing the disagreements over the lake’s management left me feeling uneasy about its future, considering how many problems are swirling around it. Right now, some 75 million metric tons of contaminated sediment are resting, uneasily, at the bottom of it, like so many buried resentments. Like many dangerous things, they’re invisible — cloaked by the beauty of the landscape. I thought of the day on the lake with the Coeur d’Alene Tribe’s scientists last fall: the moose, the drifting cattails, the calm water. I know the stats: The lake and its watershed are horribly polluted. But on that sunny October day, even as I watched the tribe’s Scott Fields and his colleagues filter water samples and measure oxygen levels, charting the health of the lake, it was hard to believe the landscape is really that hazardous. Of all the dangers facing Coeur d’Alene Lake, that may be the biggest. “Once you see the problem here,” Fields told me, “it’s way too late.”

Emily Benson is an associate editor at High Country News, covering the northwest, the northern Rockies and Alaska. Email her at emilyb@hcn.org.