The first operations for the Marcopper mine date back to 1956, when the company Placer Dome Limited became active in the area by undertaking extensive geological mapping and drilling. Mining operations started in 1969 through the exploration of the Mt. Tapian ore deposit, containing copper concentrate, as well as gold and silver. At that time, the mine was co-owned by Placer Dome Inc. (39,9%) and its partner, the Philippine dictator Ferdinand Marcos [1;2].

Between 1975 and 1991, it was estimated that more than 200 million tons of mine tailings were discharged into Calancan Bay, which covers fishing grounds of 8,000ha [2]. Complaints over leukaemia, kidney problems and other diseases among children and adults increased since 1981. First diagnosed as “common diseases”, in 1996/7, tests showed high levels of heavy metals in the blood of patients [1;3]. Moreover, local residents were protesting since 1975, as the waste dumping into the water bodies heavily affected food security of 12 fishing villages (around 15,000 persons) [2;4]. In 1988, the Pollution Adjudication Board ordered Marcopper to stop waste dumping into the Calancan bay. However, Marcopper convinced the government that dumping, having a “negligible impact”, was indispensable for the operation, and was allowed to continue if paying a remedial measure of P30,000 per day [1]. When the Tapian reserve was depleted in 1990, Marcopper continued mining in the San Antonio copper reserve, 3km north of Tapian [1]. The old Tapian pit was then used as a waste discharge disposal – an unconventional method, for which no environmental impact study was conducted [1;2].

The first disaster happened in 1993, when the Marcopper silt dam in the Maguilaguila creek collapsed and flooded nearby villages and the Mogpog River, which has long suffered from recurring floods due to siltation caused by the collapse. The colors of the river, ending in the Tablas Straight, have ranged from peach to brown to gruesome red and toxic green or violet. Flooding was so severe that several houses were swept away [1; 2]. Livestock, crops and farmland was destroyed, the river was heavily polluted and two children were drowned [1]. The second and final disaster occurred on March 24, 1996, when a massive tailing spill from the Tapian pit escaped through the badly sealed drainage tunnel and no less than 2 million tons of tailings subsequently flooded the Makulapnit and Boac river [1;2]. 700 families (3000-4000 people) from 5 villages were most directly affected and the surrounding terrestrial and aquatic environment was heavily contaminated [1]. A UN mission team visiting the area declared the situation an environmental disaster, due to the vast degradation of the rivers. It further criticized the lack of any environmental impact studies and measures, in spite of large evidence of mining spills during the foregoing years [2]. After the spill, thousands of residents needed to be evacuated and suffered isolation, hunger and diseases [1]. Many children, as well as other residents, were found to have toxic blood levels of lead and cyanide; of which some died later on from the consequences of the diseases and lead intoxication [1;3].

The year after this massive disaster, Placer Dome divested from Marcopper and left the Philippines, in absence of proper compensation of damages, or clean-up of the area [1;2;5;6]. But decades after the disaster, the region and Calancan Bay continues to be heavily silted by the mining spills and fish and agriculture continues to be contaminated with toxic metals . Fish catch was reported to have fallen from 23kg to 2kg per day, heavily affecting food security [1]. In 2001, there were still more than 800,000 m3 of tailings in the River, while the drainage tunnels were still at risk of further leaking [2]. Calancay Victims, supported by the group Upholding Life and Nature (ULAN) filed a suit for damages at the regional court [1] and in 2005, the provincial board of Marinduque filed a case in Nevada against the mining giant, who was acquired in 2006 by Barrick Gold Corporation, claiming compensation for damages, as well as environmental clean-up efforts and funds [5]. Between 2011 and 2014 mediation and settlement processes occurred, however no acceptable outcome was achieved.

As of early 2015, the case might be translated to Canada, as Barrick Gold is headquartered in Toronto. Meanwhile, the province of Marinduque aims to become a mining-free zone under national law [6]. However, the legacy of social and environmental damages will continue for decades, entailing irreversible losses, which cannot be compensated in monetary terms.

Marcopper Mining Corporation, held by Placer Development Ltd. (former Placer Dome), operated two mines on Marinduque Philippines; the Mt. Tapian Pit and the San Antonio Mine. The two mines were under operation from 1969 – 1996. [2].

Related mining tenements of Marcopper Mining Corporation in Santa Cruz covered 4,668.32ha (AMA-IVB-127 AMND); 27ha (LLA-V-271); 45ha (LLC-V-269) and 18ha (LLC-V-270) [8], totaling 4758.32ha.

In 1964, the Marcopper Mining Corporation was established and in 1969, Marcopper started its mining operations. Placer Dome owned 39.9% of shares of Marcopper, which was the legal limit of foreign involvement in Philippine companies. Until 1994, Placer Dome was the only company involved in the Marcopper mines; at least 50% of the remaining shares were held by Placer Dome’s secret partner, the Philippine dictator Ferdinand Marcos. After he was overthrown in 1986, Marco’s shares were held by the subsequent Philippines governments (Aquino and Ramos) until they were privatized in 1994 [2].

For the mining operations, loans were initially secured from a consortium of American banks [2]. Later on, also the Asian Development Bank (ADB) provided a loan amounting to 40 million USD [4]. Other creditors have been Philippine Solidbank and RCBC [7], among others.

From 1969 to 1990, a total of 779.6 million kg of copper, 23 million grams of gold, and 127.9 million grams of silver were produced [3].

After the disaster, Placer Dome Technical Services Ltd., subsidiary of Placer Dome Inc, was set up to clean up the area [b]. Placer Dome divested from Marcopper in 1997 via the involvement of Cayman Island MR Holdings Company, stating that it would continue to take responsibility for the cleanup and compensations. However, in 2001 and agreement was made, according to which responsibilities were left with Marcopper, while Placer Dome disappeared from the Philippines [2].