Ventura County Star, John Krist
Published May 13, 2001
NEVADA CITY -- Nevada County Supervisor Elizabeth Martin vividly recalls the day she learned her rural district was at the epicenter of California's most widespread industrial pollution problem.
She was attending a meeting of the Regional Council of Rural Counties, or RCRC, at which scientists from the U.S. Geological Survey had asked to speak. The researchers had information they thought might be of interest to some of the RCRC's members, who represent mostly small, politically conservative communities scattered across the Sierra Nevada and its foothills, the high desert and the Klamath-Trinity region.
The scientists had been looking for mercury-contaminated fish. They knew the toxic element could be found nearly everywhere gold mining had been conducted in the 19th century. They knew that in streams and lakes it could be transformed into methylmercury, a form that accumulates in living tissue, can be passed up the food chain and is a neurotoxin capable of causing brain damage. They also knew that mercury was traveling downstream to pollute water near distant urban areas, such as San Francisco Bay. What they wanted to know was how bad the upstream contamination really was and how difficult it might be to clean it up.
To find out, the researchers traveled to the heart of Gold Rush country, to the place where miners chewed up more countryside and spilled more mercury than anywhere else in California.
The news was not good, they told the RCRC members. Many of the fish the researchers tested in 1999 were contaminated enough to be potentially unsafe for children and pregnant women to eat. They illustrated their presentation with a map of the potential danger area, the watersheds of the South Yuba River, Deer Creek and the Bear River.
Essentially, it was a map of Nevada County Supervisorial District 4.
Martin's district.
"They showed their PowerPoint presentation, and the first thing that went up was (a slide of) the Yuba-Bear area." Martin said. They said, 'What we did was, we picked the area we thought would be the worst. And if it wasn't a problem there, it wouldn't be a problem anywhere.' "
It turned out that mercury was a problem in the Bear-Yuba watersheds. The USGS team found elevated levels in fish just about everywhere they looked in Martin's district.
Knowing that a problem exists, however, is not the same as being able to solve it. The dimensions of California's mercury contamination are daunting, constituting a vast, toxic bequest from the 19th century to the 21st. That unwelcome legacy ties the state's high-tech present to its rambunctious past and in coming years will unite rural mountain counties and coastal metropolitan areas in a search for solutions.
The Mother Lode
Generations of California schoolchildren have been introduced to the traditional image of the 49er, icon of the gold rush. He's a bearded guy in flannel and denim carrying a pick and a pan, wandering the stream-cut canyons with his trusty burro in solitary pursuit of riches.
It was a bit like that in the first few years after James Marshall found gold in the tailrace of Sutter's Mill beside the American River. But the rich, easy-to-work deposits were exhausted within a decade after Marshall's 1848 discovery. Gold mining in California then became a large-scale industrial activity, one requiring great infusions of investment capital to erect the elaborate infrastructure -- mills, rail lines, dams, flumes, smelters -- required to separate tiny quantities of gold from the vast deposits of buried gravel and bedrock in which it was mixed.
There were two basic ways to do this, depending on whether the gold was trapped in solid rock ore or mixed with sand and gravel. Mercury became a crucial ingredient in both processes. It is heavy, and easily combines with other metals to form an amalgam. Miners learned to use it as a trap, a metallic tar baby to keep the gold from getting away.
In stamp mills, where gold-bearing ore was pounded into dust by heavy iron shoes driven by steam engines, the pulverized debris was allowed to wash across long copper plates coated with mercury. Fine bits of gold would sink and stick, while the more buoyant rock debris flowed away on the stream of water. Periodically, mill workers would shut down the stamps and scrape the mercury-gold amalgam into balls. These would be cooked in furnaces, vaporizing the mercury and leaving behind the gold.
Much of the evaporating mercury was captured in a condensation chamber for re-use. Some escaped into the air. Some was pulverized by the iron shoes of the stamp mill and floated away in the water, making its way into nearby streams.
The biggest source of mercury contamination in the California environment, however, was the practice known as hydraulic placer mining.
Fifty million years ago, the landscape that now constitutes the Sierra Nevada foothills was a low coastal plain. Across it wound huge and powerful rivers, which deposited vast quantities of sand and gravel in their beds. Those deposits, eventually buried and then lifted by the titanic forces that created the Sierra Nevada itself, were laced with gold. They became famous worldwide as "the auriferous gravels" ("auriferous" being Latin for "gold-bearing") and they eventually yielded a quarter of all the gold mined in California.
In 1853, a miner named Edward Matteson figured out a safe and efficient way to excavate those placer deposits, some of which were hundreds of feet thick. ("Placer" is Spanish, and refers to a sand bank or shoal; it also means "pleasure" and might connote the ease with which such deposits could be worked). He and his partners fashioned a brass nozzle, attached it to a rawhide hose and used a blast of water to wash away the gold-bearing gravel.
The technique caught on and spread. Eventually, mining companies diverted entire creek systems into reservoirs, feeding that water at high pressure through aqueducts and steel pipes to huge nozzles known as "monitors" or "giants." Resembling military cannons, some of them 16 feet long, they could deliver up to 30,000 gallons a minute in a nine-inch stream at a pressure of 125 pounds per square inch. Directed at the gold-bearing gravel, this liquid artillery barrage could level entire hillsides -- rock, soil, forest -- with startling efficiency.
It is difficult to appreciate the scale of landscape rearrangement made possible by this rather crude technology. The biggest such mining operation was in Nevada County, upstream from Martin's supervisorial district. Now preserved within Malakoff Diggins State Historic Park, the hydraulic mining operation there managed to wash away 41 million cubic yards of gravel, sending it all downstream into the Yuba River and its tributaries. The resulting pit was 7,000 feet long, 3,000 feet wide and more than 600 feet deep. Although partially filled by erosion, it remains a startling sight today: a huge man-made analog to Utah's Bryce Canyon, with multicolored walls eroded into fantastic shapes.
The debris brought down by the monitors was directed into sluices containing mercury. Sometimes the sluices were wooden troughs with perpendicular cleats in the bottom; mercury was dumped behind the cleats to trap the gold. At other mines, ground sluices were used. Miners would simply pour liquid mercury into long trenches or tunnels dug into the ground below the mining pit and wash the gold-bearing gravel through them.
As it washed through the sluices, leaving behind its gold, the gravel and sand (henceforth referred to as "tailings") became contaminated with mercury that either leaked from the sluices or was washed away by the flowing water. This is the essence of California's Gold Rush pollution problem.
Nearly unimaginable quantities of debris washing downstream from the Sierra Nevada hydraulic mines choked rivers and buried farmland all the way to San Francisco Bay. The Sacramento River rose seven feet in elevation as its bed was inundated with sand and silt. Great fans of milky white gravel, sand and cobbles -- the water-polished legacy of those 50 million-year-old rivers -- filled canyons throughout the mining belt and spilled 10 miles out across the Central Valley. More than a billion cubic yards of tailings washed into San Francisco Bay, impeding navigation and turning the ocean brown at the Golden Gate.
Before the practice was largely halted by an 1884 court ruling, hydraulic miners sent 1.6 billion cubic yards of sediment into the state's waterways, according to Charlie Alpers, a USGS research chemist. Hard-rock miners produced 30 million cubic yards of tailings. Dredges, which used mercury to process sand and gravel scooped from river channels and flood plains, left about 4 billion cubic yards of debris heaped alongside streams. Altogether, gold miners picked up and moved about 5.6 billion cubic yards of California.
Spread a foot deep, that much debris would cover 5,424 square miles. Connecticut has an area of 5,544 square miles.
According to Ronald Churchill, who surveyed historical data to arrive at an estimate for his employer, the state Division of Mines and Geology, early hydraulic miners "lost" as much as one pound of mercury for every three or four ounces of gold they recovered.
A standard household fever thermometer contains a half a gram of mercury, enough to contaminate a 25-acre lake to the degree that its fish become unsafe to eat. A pound of mercury is enough to fill about 900 thermometers.
Operations eventually became more efficient (and dredging was never quite as sloppy as hydraulic mining). Still, Churchill estimates that gold miners in California lost about 12.8 million pounds of mercury in the 19th and early 20th centuries, 80 to 90 percent of it in the Sierra Nevada. Enough mercury, in other words, to fill more than 11.5 billion household thermometers.
Most of it is still out there. Somewhere.
The Coast Ranges
The Sierra Nevada gold fields are not the only source of mercury released into the California environment. In a geological coincidence that gratified the mining industry but has brought no joy to modern-day public health experts, the state is one of the few places in the world to possess both rich gold deposits and abundant natural sources of the mercury so helpful in gold extraction.
Mercury ore, primarily a form known as cinnabar -- a reddish rock, in which mercury forms a compound with sulfur -- occurs in the Coast Ranges between Clear Lake and Santa Barbara County. The deposits are some of the richest in the world. Between 1846 and 1981 they produced 227 million pounds of mercury, Churchill estimates. Half the total came from the two largest of the mines -- New Idria (northwest of Coalinga) and New Almaden (12 miles southwest of San Jose, now a Santa Clara County park with a stunning view of Silicon Valley).
In 1861, a state geological survey team visited New Idria, named after the Idria mining region in Yugoslavia (New Almaden was named after the Almaden region in Spain, the richest mercury deposit in the world.) Member William Brewer's journal of that survey, "Up and Down California in 1860-1864," offers a glimpse into the business of 19th-century mercury production, and it is not a romantic one.
"Sulphurous acids, arsenic, vapors of mercury, etc., make a horrible atmosphere, which tells fearfully on the health of the workmen," Brewer wrote, "but the wages always command men and there is no want of hands. The ore is roasted in furnaces and the vapors are condensed in great brick chambers, or 'condensers.' These have to be cleaned every year by workmen going into them, and they may have their health ruined forever by the three of four days' labor, and all are injured; but the wages, twenty dollars a day, always bring victims. There are but few Americans, only the superintendent and one or two other officials; the rest are Mexicans, Chileans, Irish (a few) and Cornish miners."
From 1850 to the 1890s, California was the only source of mercury in the United States. Production greatly exceeded domestic demand, and 70 percent of California's mercury was exported, mainly to other Pacific Rim countries.
Much of what remained was hauled across the state to the gold fields or to mining regions elsewhere in the West. (A major destination was the rich Comstock Lode in Nevada, about 20 miles east of Lake Tahoe, where an estimated 14 million pounds of mercury ended up in the Carson River). Mercury escaped into the environment wherever it was mined and processed -- spilled during handling, escaping up the chimney during refining, absorbed into the bricks of the refinery furnaces themselves. Churchill estimates that 75.9 million pounds of mercury may have been lost to the environment in California during cinnabar mining and refining.
More significantly, the mining operations left behind vast quantities of mercury-contaminated tailings and ore. As a result, the old mines today continue to send mercury into creeks, rivers and lakes. Eleven of the 12 water bodies where the state has issued fish consumption warnings because of methylmercury are contaminated exclusively by old mercury mines; the 12th, the San Francisco Bay-Delta region, has been contaminated by mercury and gold mining operations.
According to records kept by the California Department of Conservation and the U.S. Bureau of Mines, at least 239 mines in the state produced at least one flask of mercury. (A flask is the standard industry measurement, referring to a steel bottle shaped like a squat scuba tank that contains about 76 pounds of mercury.) Another 54 sites may have had unrecorded production.
Government records list about 13,500 historic gold mines and prospects in California, most in the Sierra Nevada but a significant percentage in the Klamath-Trinity mountains in the northwestern part of the state.
Nearly any of these thousands of mercury and gold mines could be a source of contamination, rendering fish downstream unsafe for children and pregnant women to eat.
The past is alive
In most cases, the standard approach to discovery of a dangerous environmental contaminant is to clean it up:scrape off the asbestos, scoop up the crude oil, haul away the pesticide-laced soil. To understand what it might mean to clean up California's mercury-contaminated mining areas, perhaps the best place to look is Greenhorn Creek, a small tributary of the Bear River in Elizabeth Martin's supervisorial district. This is not just because Greenhorn Creek is a scenic, peaceful place for a picnic -- although it certainly is that -- but because of the story it tells.
To reach the creek, you must drive for several miles out of Nevada City (the county seat, location of the government center where Martin has her office), following a succession of progressively narrower, rougher roads. Eventually the route becomes dirt and descends into a canyon carved through forested slopes.
The road ends at the lip of the stream bed. Greenhorn Creek is nearly lost as it wanders in sparkling braids across a vast expanse of white gravel, sand and cobbles. The debris is almost Saharan in its apparent lifelessness. Protruding from the blinding expanse of rock are what look like charred tree stumps.
To a geology buff, the polished, quartz-rich rock and sand filling the creek bed are instantly identifiable. They are the fabled "auriferous gravels," the gold-bearing deposits laid down by long-lost rivers as big as the Yukon. The gravel is here because 150 years ago there was a hydraulic mining operation upstream.
The tree "stumps" are actually the tops of mature Douglas firs, perhaps 150 feet tall, buried from root to crown by a 200-foot blanket of hydraulic mining tailings swept into the canyon more than a century ago. Partially exposed now by erosion, the trees are rooted along the original bank of Greenhorn Creek, which lies 100 feet beneath the gravel.
All that gravel is mixed with minute quantities of mercury, which is adding to the toxic load in rivers and lakes downstream. How much would it cost to remove it, even if such a thing were technically feasible? And what about the scores of other creeks and canyons just like it throughout the heart of California gold country?
"The idea of removing all the mercury from the watershed is pretty unrealistic," said Alpers, whose agency has proposed additional studies in the region to help explain how mercury behaves once it enters the aquatic environment.
"Everywhere they did gold mining, they did a couple of things," Martin said. "One thing they did was redirect all the water in the area through sluices. They used sluices to do this mercury treatment. So, they basically replumbed the Sierra Nevada to run (its rivers) through sluices where mercury was applied. Today, the watershed still runs into the same old tunnels, the same old watercourses, which are very different than what we had 200 years ago. No one is thinking we're going to be able to go back to the landscape of more than 150 years ago, but we need to identify where those hot spots are."
Even identifying particularly "hot" sources of mercury contamination can lead to a difficult and costly cleanup. The EPA recently spent about $1.4 million to remove mercury from a single 500-foot long tunnel at the Polar Star mine in Placer County. It spent $2 million partially cleaning up two modest mercury mines in San Luis Obispo County. It has spent more than $1.5 million on preliminary work at the Sulphur Bank mercury mine on the shore of Clear Lake and still has years of work left to do.
Contaminated streams and lakes are not the only issues facing Martin and other public officials in gold country. Land use is also affected by mining's toxic legacy. Builders and subdividers naturally are drawn to the rare flat spots in the rugged foothills topography, but in most cases those flat spots are the result of mining excavation.
Opportunities for developers to run afoul of mercury contamination in the soil are increasing. Foothills communities are among the fastest-growing areas of California, according to the 2000 Census, particularly in gold country. Placer County's population swelled 43.8 percent between 1990 and 2000, the second-highest growth rate among California's 58 counties. El Dorado County grew 24.1 percent, ranking ninth. Nevada County didn't grow quite as fast, but it still made it into the top half: Its population increase of 17.2 percent ranked 25th.
That's one of the reasons Martin was so disturbed to learn of the 1999 USGS study finding elevated levels of methylmercury in fish from streams and lakes in her district.
"We immediately became alarmed that we were going to suddenly be ordering landowners to do mercury evaluations, which were going to cost gazillions of dollars, and then they're going to discover that their land is contaminated and they can't build on it," she said.
Mercury also has potentially costly implications for local government as federal regulators begin imposing limits on the amount of that contaminant in the discharge from sewage treatment plants -- mercury that, for the most part, enters the municipal system in the water supply.
"Every little gold country sanitation system is going to have to be looked at," Martin said.
Already, state and federal taxpayers are spending millions of dollars to study the effect mercury contamination might have on plans to restore salmon and steelhead runs in the northern part of the state. Among the key strategies being examined under CALFED, a state-federal partnership launched in 1994 to rectify a host of problems besetting the Sacramento-San Joaquin river delta, is restoration of tidal marsh around San Francisco Bay and removal of key upstream dams -- among them the 260-foot concrete arch at Englebright Lake, one of the reservoirs identified by the USGS as harboring contaminated fish.
Wetlands are critical nurseries for young fish, but they also are known to be places where toxic elemental mercury is transformed into methylmercury, the neurotoxic form that makes its way into fish. And removing Englebright Dam would open up many miles of potential spawning habitat but also would send millions of cubic yards of contaminated sediment downstream.
The presence of a dangerous contaminant in the scenic lakes and mountain streams also is annoyingly ironic to Martin and other community leaders. Like other rural areas in the American West, Nevada County and its neighbors are trying to make the bumpy transition from an economy based on natural-resource extraction -- mainly mining and logging -- to one based on tourism, recreation and service industries attracted by the quality of life the cool, pine-studded mountains offer their employees.
Fishable lakes and streams are a big part of the area's lure. So are the charm and historical interest conferred by its mining past. It seems a cruel jest now to learn that the mining legacy drawing visitors to the museums, parks, shops and inns of gold country might also poison them if they eat too many of its fish.
Everyone lives downstream
Whether they realize it or not, urban communities in the Central Valley and along the California coast have a stake in the future of the foothills, and Martin hopes to capitalize on that to clean up the mess in her own back yard.
Sacramento County, for example, has been ordered by the Central Valley Regional Water Quality Control Board to limit the amount of mercury in its sewage discharge to the Sacramento River. Unless it can find a way to keep mercury from entering the municipal system in the first place, it will have to install costly treatment equipment. Martin would like to see that money invested instead in cleaning up a primary source of mercury in the river: old mining debris in the mountains.
The problem is even more acute in the San Francisco Bay area. The bay is downstream from 40 percent of the state and receives 80 percent of its runoff. This vast estuary, largest on the West Coast, also lies at the heart of a metropolitan region that's home to 6.7 million people, and it receives discharges from 36 municipal sewer plants and 18 industrial treatment plants.
Water containing mercury flows into the bay from every side, although the biggest single source appears to be the abandoned New Idria and New Almaden mines to the south, according to Khalil Abu-Saba, an environmental specialist with the San Francisco Bay Regional Water Quality Control Board.
The bay also received huge quantities of hydraulic mining debris in the 19th and early 20th century before dams were built in the foothills and reservoirs became receptacles for the flood of tailings. At the north end of the bay, where it pokes into Napa and Marin counties, the bottom is buried beneath six feet of mercury-contaminated gold mining debris, Abu-Saba said.
As a consequence of mining, the bay's fish are contaminated with methylmercury. The state has issued warnings to limit consumption of all sport fish caught there, with particular cautions against striped bass and shark. The striped bass warning for pregnant women and children has been in effect since 1971.
Unlike vacationers who pull a few trout or bass once a year from a lake or stream in Sierra Nevada gold country, people who fish on San Francisco Bay are more likely for economic or cultural reasons to eat a lot of what they catch. They are therefore more likely to be at risk of suffering ill effects from methylmercury exposure. In recognition of this, the Save the San Francisco Bay Association received an EPA grant five years ago for a program offering at-home workshops directed primarily at Hispanic and Asian households on how to avoid eating contaminated fish.
Abu-Saba is working to develop a total maximum daily load, or TMDL, for mercury in San Francisco Bay. A TMDL sets a limit for the amount of a particular contaminant entering a body of water, intended to ensure that it meets federal Clean Water Act standards. The Regional Water Quality Control Board allocates a percentage of that total load to each source of the pollutant in the watershed. Those sources -- industrial facilities, municipal sewer plants, water agencies -- must then reduce their emission of that pollutant to meet their share of the TMDL.
The mercury TMDL ( a draft version of which was released last summer) will be intended to cut the amount of mercury in the bay by half, Abu-Saba said. That would still be higher than the background level -- a consequence of natural processes such as erosion of ore deposits and emissions from volcanoes and geothermal springs -- which researchers have determined by analyzing core samples of bay sediments from before and after the mining era. Nevertheless, he said, it should be enough to keep the levels in fish tissue low enough to be safe.
Filtering mercury from waste discharges can be an expensive proposition. It is possible that the TMDL standards might send Bay area industries and public agencies searching upstream for the source of the contaminant. If so, Martin and other community leaders in gold country will welcome them, as long as they bring money.
"They have the health cost," Martin said. "We're going to have the economic impacts."
Cooperation makes sense to the rural upstream towns, because big cities and big industry -- which face the costliest consequences of mercury in California's environment -- have the money to do something about it. The small rural counties, where the problem originates, do not.
Cooperation makes sense from another standpoint. Mercury pollution, after all, respects no political boundaries. Although a significant share of the mercury coming into San Francisco Bay arrives in municipal and industrial wastewater discharges from the necklace of cities encircling it, the biggest source is old mines and mining debris elsewhere in the state. A small but measurable contribution also comes from the atmosphere and is a consequence of fossil-fuel combustion -- the leading artificial source of mercury released into the environment -- thousands of miles away.
"This is a global problem," Abu-Saba said. "I don't have regulatory authority over airborne emissions from China."
-- John Krist's e-mail address is
krist@insidevc.com
"We immediately became alarmed that we were going to suddenly be ordering landowners to do mercury evaluations, which were going to cost gazillions of dollars, and then they're going to discover that their land is contaminated and they can't build on it."
-- Elizabeth Martin, Nevada County supervisor,
recalling her reaction to a 1999 study that found elevated levels of methylmercury in fish in her district
Senior writer John Krist spent five months researching a comprehensive report on mercury contamination. A three-day series starts Sunday.
Sunday
UBIQUITOUS: Scientists are just now beginning to grasp the full extent of global mercury contamination.
Monday
STATE PROBLEM: California's toxic gold rush legacy unites rural and urban communities in a search for solutions.
Tuesday
UNCERTAIN IMPACTS: Efforts to reduce mercury exposure are complicated by the element's ability to travel long distances and by uncertainties regarding the actual health risk it poses in the environment.
More online
Here are some Web sites that provide useful information about mercury in the environment and its implications for human health:
California Office of Environmental Health Hazard Assessment's listing of fish consumption advisories:
www.oehha.ca.gov/fish/general/index.html.
Environmental Working Group's report, "Brain Food," calling for stricter federal regulation of methylmercury in fish:
www.ewg.org.
The Mercury Policy Project:
www.mercurypolicy.org.
U.S. Environmental Protection Agency's mercury page:
www.epa.gov/mercury.
U.S. Geological Survey overview of mercury in California: ca.water.usgs.gov/mercury.
EPA's Mercury Study Report to Congress:
www.epa.gov/ttnuatw1/112nmerc/mercury.html.
