Lessons for Northern Minnesota From 5000 years of Copper/Sulfide/Acid Mining in  Spain, Followed by a Single Generation of Failed Remediation Attempts - and You Still Can’t Drink the Water! (and you never will)

Spain’s Rio Tinto (“Stained River”) Estuary: one of the Most Polluted Areas in the World – Thanks to Sulfide Mining

By Gary G. Kohls, MD, Duluth, MN

“The Rio Tinto system in southwestern Spain….is one of the most polluted fluvial-estuarine systems in the world and most likely has been so for thousands of years.”

”The city of Huelva, Spain, has become the site of one of the most polluted industrial areas of the world.”

“Spain's Rio Tinto is characterized by deep red water that is highly acidic (pH 1.7—2.5) and rich in heavy metals

“The contaminants that have cursed every area where copper sulfide mining has been tried, include the highly toxic heavy metals Lead, Mercury, Arsenic, Nickel, Zinc, Cadmium, Vanadium Antimony and Manganese”.                                         

The Rio Tinto river, pictured above, acquired its name centuries ago because of its reddish color, a color it has been (in)famous for ever since ancient people used primitive methods of extracting copper in the area even before the Roman Empire also heavily exploited the area centuries later for metals such as lead, copper, silver and gold.

The undrinkable, permanently poisoned water in the Rio Tinto watershed extends all the way down to the edge of the now-polluted salt-water of the Atlantic Ocean estuary downstream. That once-thriving ancient fishery has long-since been decimated because of the continuous flow of toxic water over the centuries – thanks to sulfide mining. The Rio Tinto, from its source all the way down to its mouth, has the acidity of stomach acid (< pH 2.5), as does the water that is gradually filling the abandoned open pit sulfide mine also pictured above. The abandoned underground copper mines also contain highly poisonous water. Thanks to sulfide mining.

Holden Village, Lake Chelan and Copper Sulfide Mining

Ask me sometime about Holden Village, the Lutheran Church’s family retreat center near the headwaters of Lake Chelan, Washington. My wife and I have spent a handful of retreats there over the years. I recall being intrigued by the unearthly blue-green color of the water where the boat dropped us villagers off at the dock upon arrival. Now I understand where the color came from and why it was so naïve of me to have considered bringing fishing gear with me at our next visit.

Holden Village was started from scratch in 1938 as a remote company town (no roads; only access to the outside world was by boat) that housed miners and their families. The villagers lived a short walking distances from the underground copper mine that was built by the Howe Sound Mining Company of Canada (!). After 19 years of mining Howe suddenly abandoned the mine and the village, turned off the water pumps (that kept the mine dry enough to mine), fired its hundreds of miners, leaving behind a ghost town, a permanently-poisoned underground copper mine, a huge toxic dry tailings dump (that was situated immediately adjacent (!) to a now highly contaminated (ex-)trout stream that then flowed into the newly-contaminated Lake Chelan which had, of course, received unknown millions of gallons of poisoned water ever since 1938.

World copper prices plummeted in 1957 and Howe Sound immediately closed the mine, giving no advance warning to its employees. Holden Village was destined to become another classical mining ghost town, except for the fact that the company gifted the town to several Lutheran church denominations in 1960 (after failing to sell it for $100,000). The Lutheran church soon established a family retreat center that is thriving to this day, except for the trout, for they cannot survive in the still-poisoned downstream Railroad Creek. Thanks to sulfide mining.

Interestingly, because of a series of mergers and acquisitions, the Rio Tinto Mining Company acquired the responsibility of remediating Holden Village’s dry tailings dump, which had been designated a SuperFund site by the EPA. Great Britain-based Rio Tinto has been a powerful multinational mining corporation ever since the late 1800s, when the company started exploiting and contaminating Spain’s copper sulfide mining region. The company has spent the past few years at Holden Village remediating the site by constructing a deep walled structure that is designed to stop toxic drainage from the tailings every time it rains and to hopefully keep an earthquake from de-stabilizing the mound of toxic wastes that could suddenly empty its toxins into Lake Chelan. The underground mine is off-limits to curious explorers only because the water has those toxic heavy metals dissolved in it and because the pH of the water at the mine mouth is <2.5 and will remain so for eternity. Thanks to sulfide mining.

But I digress.

Reckless Endangerment of Northern Minnesota’s Water-Rich Environment – for the Love of a Lousy Buck

Highly acidic water is incompatible with > 99% of aquatic life and cannot be economically converted back into drinking water, even with high-tech (and unaffordable) reverse osmosis techniques that have been deceptively suggested by PolyMet salespersons as a possible remediation technique for the millions of gallons of poisoned water that it will inevitably produce.

But there is something even worse than the sulfuric acid-contaminated water is the presence of highly toxic heavy metals that are in both the sulfide sludge in the tailings ponds, the water in the aquifers below the ponds and pits and in the water (even rain water) that was in contact with the sludge. And that reality is the presence of the neurotoxic and carcinogenic heavy metals that are, when they reach sufficient concentrations or combinations, also incompatible with life and health.

The contaminants that have cursed every area where copper sulfide mining has been tried, include the highly toxic heavy metals Lead, Mercury, Arsenic, Nickel, Zinc, Cadmium, Vanadium Antimony and Manganese.

Northern Minnesota’s rivers and lakes that are in the vicinity or are downstream from PolyMet’s proposed – and very ill-advised - tailings lagoon are being recklessly endangered. The soluble earthen dam that will eventually “contain” the millions of cubic meters of toxic sludge will be a highly unstable 250 feet tall!

PolyMet’s state-of-the-art “containment” (theoretically-speaking) dam that will supposedly hold back the massive volumes of liquified toxic sludge for an eternity will be of a type not much different than the infamous Mount Polley, British Colombia tailings “pond” (with “only” 130 feet high earthen dam walls) that burst (on August 4, 2014) and destroyed and permanently poisoned downstream streams, lakes and rivers.

Copper Mining Catastrophes Can Happen Here

Such mining catastrophes can happen here, and the wate include the Partridge River, the Embarrass River, the St Louis River and Lake Superior are being cavalierly risked for “the love of a lousy buck”, as Minnesotan and Iron Ranger Bob Dylan put it in his song, “When the Night Comes Falling From the Sky”. That powerful song expresses some of the hopes, fears, insights and sentiments being experienced right now by those worthy, well-informed, under-funded and very altruistic environmentalists who are fighting against powerful uber-wealthy corporate influences and their political, bureaucratic, business and Big Media allies for the sustainable future of northern Minnesota and its life-giving water.

Dylan writes: “I can see through your walls and I know you’re hurting;

Sorrow covers you up just like a cape;

Only yesterday I know that you’ve been flirting

With disaster you somehow managed to escape.”


“I saw thousands who could have overcome the darkness

But for the love of a lousy buck, I’ve watched them die.”



As readers (including politicians, mayors, city council members, DNR bureaucrats, PCA bureaucrats, Forest Service bureaucrats newspaper editors and writers and especially Senator Amy Klobuchar, US House of Representative member Rick Nolan, Governor Mark Dayton, all Iron Range politicians such as David Tomassoni, Tom Rukavina, Tom Bakk and all prospective politicians wanting to attract votes, to read and then study this document, and then mentally substitute the words “Duluth”, “Minnesota”, ”St Louis River” and “Lake Superior” whenever the words “Huelva”, “Spain”, “Rio Tinto” or “Atlantic Ocean” appear.

The photos, the above exercise and the scientific information below will convince every open-minded, good-hearted, trustworthy, caring person to reject, protest against, vote against and otherwise obstruct the reckless attempts by some of the above-noted entities that are, so far, being successfully bamboozled by the sociopathic, un-documented, foreign mining corporations like PolyMet, Glencore, Twin Metals and Antofagasta in their selfish attempts to risk



Excerpts below are from the September 2000 edition of the University of South Florida’s Scholar Commons

Posted at:

The Rio Tinto Estuary (Spain): 5000 years of Pollution

R.A. Davis Jr. 7 A.T. Welty 7 J. Borrego 7 J.A. Morales 7 J.G. Pendon 7 J.G. Ryan


Mining of massive sulfide deposits in southwestern Spain extending back to the Copper and Bronze Ages has resulted in the pollution of the Rio Tinto fluvial-estuarine complex, the site of Columbus’ departure for the New World in 1492. Additional sources of potential pollution include the large industrial complex at Huelva near the lower portion of the estuary. Extensive analysis of surface sediment samples and cores has established that there are no geographic trends in the distribution of the pollutants, which include Cu, Fe, Pb, Zn, Ti, Ba, Cr, V and Co.

These data have, however, demonstrated that tidal flux within the estuary carries phosphorus and perhaps other elements from the industrial complex at Huelva to the tidal limit of the system, several kilometers upstream from the discharge site. Radiometric analysis of short cores shows that sedimentation rates over at least the past couple of centuries have been about 0.3 cm/ year. These data and that from a single deep core demonstrate that the estuary was polluted from mining activity long before the large-scale operations began in the late nineteenth century.

Key wordsSediment pollution;  Massive sulfides;  Phosphate; Open-pit mining; Estuary Cases and solutions.


The Rio Tinto system in the province of Huelva, southwestern Spain, has great historical significance as well as environmental interest. It is one of the most polluted fluvial-estuarine systems in the world and most likely has been so for thousands of years. It is in the headwaters of this river that mining supporting the Copper Age and Bronze Age took place. The estuary, at the town of Palos de la Frontera, was the origin of Columbus’ expedition in 1492 and for subsequent trips. Most recently, the city of Huelva has become the site of one of the most polluted industrial areas of the world. It is possible, however, that the pollution of the system began thousands of years ago with the original mining of the massive sulfide deposits near the headwaters of the Rio Tinto.

This investigation was conducted in order to answer the following questions:

1. What is the level and distribution of metals and other important pollutants in the sediments of the system?

2. What is the influence, if any, of tidal transport of the pollutants being discharged in and near the industrial complex at Huelva?

3. What is the chronology associated with the pollutants and to what extent, if any, have they been incorporated into the sediments that have accumulated in the estuary?

Study area

The massive sulfide deposit called the Iberian Pyrite Belt is one of the largest and most famous of such deposits in the world. It extends in essentially an east to west orientation across about 250 km of southwestern Spain and southern Portugal (Fig. 1) with an average width of 30–40 km. The thickness of the complex ranges up to hundreds of meters. The rich ore body is limited to a length of 5 km and is 750 m wide and 40 m thick. These sulfides were formed in the early Carboniferous, about 300–350 Ma, over a sequence of Devonian shales and quartz arenites and are overlain by Lower Carboniferous turbidites (Moreno 1993). The mineralization was produced by tremendous hydrothermal activity on the sea


Historical perspective

Mining of these massive sulfide deposits has been going on for about 5000 years, beginning with the Iberians and Tartessans who developed the first mine about 3000 b.c. near the present community of Nerva (Fig. 2). This underground, small-scale operation was followed by that of the Phoenicians (2800–2600 b.p.) and the Romans (2000–1800 b.p.). The area is the site of the beginnings of the Copper Age and the Bronze Age (Coles and Harding 1979), and the Romans made some of their first coins from materials mined here, especially the silver and gold. Subsequent cultures, including the Visigoths (1600– 1300 b.p.) and Moors (1300–500 b.p.), essentially abandoned the mining operations.

Then in the nineteenth century the mining was taken over by the United Kingdom, and large-scale, open-pit operations prevailed until the deposits had been essentially depleted about a century later. Peak production for the large volume products such as pyrite was between 1875 and 1930 (Ferrero 1988). The copper production was stopped in 1986 and silver and gold production ended in 1996. A much smaller-scale copper production was initiated again in 1994 but proved uneconomic and was halted in 1998.

The amount of material excavated from these ancient operations has been estimated from the volume of waste produced. The Tartessans removed about 3 million tons using small galleries and shallow depths with typically only one or two people working the mine. The Romans expanded the operations with larger galleries and greater depths. They dug below the water table and used clever water-wheel systems to pump the galleries dry. These operations accounted for about 24.5 million metric tons of material (Flores 1979). The expansion of the mining to open-pit methods led to the total production of about 1600 million metric tons of material.

The other and recent aspect of the potential pollution of this fluvial-estuarine system is the industrialization of the Huelva area beginning in 1967. Within only a few years, operations began of (1) a huge phosphate beneficiation plant which processes raw ore from nearby Morocco and other locations, (2) a plant for processing Australian heavy minerals such as magnetite and ilmenite (“black sand”) and (3) a large paper mill located at San Juan del Puerto.

Each of these industries is contributing huge volumes of pollutants to the local estuaries. The phosphate plant has produced millions of tons of phospho-gypsum which is piled along the west margin of the Rio Tinto estuary (Fig. 2). Tailings of the pyrite plant are similarly located and the paper plant discharges a large volume of contaminated wastewater.


Water quality of this estuary is extremely poor with low tide pH values typically at 2.0–2.5. Flood tides bring in Atlantic water and raise the pH to near neutral levels in the lower portion of the estuary. There is no macrobenthic community and only during flood tides are there nekton or plankton in the estuary. The only organisms in the river portion of the system are microalgae, bacteria and fungi (Moreira and others 1997).

The estuarine portion of the Rio Tinto system is characterized by braided channel systems of gravel, sand and mud with terrigenous gravel being limited to the uppermost portion. Tidal channels are typically floored by bedforms in sand with mud concentrated on the channel margins and in the lower intertidal zones. Shell material is conspicuously absent from the surface sediments of the estuary.


Important pollutants included in the analyses are Fe, Ti, Ba, Ni, Co, Cr, V, Zn and Cu.Other species concentrations that were determined, such as Al, Mg, Ca, K and Na, are either not important constituents of the ore body, or are not major pollutants, or they could come from sources such as the turbidites associated with the massive sulfide deposits.


…recent investigation of heavy metals was undertaken for 12 sites from the mine area to the mouth of the estuary (Schell and others 1996). These studies all concluded that there were quite elevated concentrations of many heavy metals (e.g. Pb, Cu, Ca, Mn, As, Zn, Fe, Ag) in the estuaries as a consequence of the mining activities. They did not address the contributions of the phosphate plant at Huelva nor the influence, if any, of tidal flux in distributing these pollutants.

All authors agree that the mining began about 5000 years ago but few have tried to unravel the chronology of the significant pollution in the fluvial-estuarine system.



Analysis and interpretation of a system-wide suite of surface sediment samples, four pound cores and three vibracores from the Rio Tinto fluvial-estuarine system permits the following important conclusions:

1. The data collected from the mines themselves to the mouth of the estuary corroborate that of other investigators in that there are highly elevated concentrations of numerous pollutant oxides and trace elements in surface sediments.

2. Likewise, our data do not show any downstream trends, high concentrations occur throughout the system.

3. Effluent produced by the phosphate beneficiation system in the Huelva industrial complex is being transported upstream to the tidal limit of the estuary as evidenced by elevated phosphorus concentrations.

4. Benthic fauna, especially oysters and clams, were able to exist and reproduce under very polluted estuarine conditions

5. Most importantly, it has been determined that the Rio Tinto system was polluted by mining activities well before the large-scale, open-pit practices of the late nineteenth century.





Veins of sulfide minerals come from deep underground where they are in a chemically reduced form. When they (sulfides) are exposed to the water and air at the surface, the minerals proceed to oxidize and liberate their ingredients. The metals in the sulfides may move away along with the sulfur compounds, which generally oxidize to sulfuric acid (H2SO4), but oxides of iron and aluminum tend to stay put. A large sulfide deposit, as it ages at the surface, may gradually gain a thick cap of iron oxide minerals - a gossan. "Gossan" may also mean the red oxide material itself.

The word "gossan" comes from the Cornish language and refers to the red color of the oxidized iron minerals. It may also be called an iron hat or the French chapeau de fer or the German eisenhut.

Gossans are primarily iron oxides such as hematite and goethite, or the intimate mixture of both called limonite. In the old days these might have been of interest as iron ore, but their real value to prospectors was as a sign of ore deposits underneath. And in addition to iron, gossans concentrate native gold and silver.


Rio Tinto, Spain


Created by Sarah Bordenstein, Marine Biological Laboratory


Spain's Rio Tinto is characterized by deep red water that is highly acidic (pH 1.7—2.5) and rich in heavy metals. Over 5000 years of mining pollution have contributed to the river becoming an extreme environment, although the presence of chemolithotrophic organisms, such as iron-oxidizing bacteria and sulfur-oxidizing bacteria, are thought to be the true culprits to the river's condition. Home to many unusual organisms, the most remarkable findings to date may be the unexpected degree of eukaryotic diversity in the acidic water. The diversity of these eukaryotes, both alkaliphilic and toxitolerant, is much greater than that of the prokaryotes, thus challenging beliefs that extreme environments are always dominated by Eubacteria and Archaea.

The Rio Tinto holds a significant role in history as the birthplace of the Copper Age and Bronze Age. The first Rio Tinto mines were developed in 3000 b.c. by the Iberians and Tartessans. Tales of mineral wealth (gold, silver, and copper) drew the Phoenicians (2800 b.p.—2600 b.p.) and then the Romans (2000 b.p. - 1800 b.p.), who made some of the first coins from Rio Tinto's silver and gold. Other cultures, including the Visigoths (1600 b.p.—1300 b.p.) and the Moors (1300 b.p. to 500 b.p.), eventually abandoned the mines. The mines were rediscovered by Spain in 1556 and reopened in 1724, only to be sold to the British in 1871. They are now one of the most important sources of copper and sulfur in the world.

The origin of Columbus' 1492 expedition, the Rio Tinto is still creating history. It is now an expedition target for the Mars Analog Research and Technology Experiment (MARTE). MARTE is drilling for core samples and testing satellite links from Rio Tinto in preparation for remote robotics that may one day survey Mars. Thought to be a close analog to that of the Martian subsurface, Rio Tinto's extreme environment could also represent a unique biological setting to explore sulfur-based life on Europa. Therefore, understanding the extremophiles that live here contributes to our search for extraterrestrial life.