metal poisoning. Mining disaster This disaster at the Marcopper Mines on Marinduque made headlines around the world. In August 1996, a significant leak was discovered in the pit's drainage tunnel. The leak caused a fracture which discharged tailings into the Makulapnit-Boac river system. This released over 1.6 million cubic meters of tailings along 27 km of the river and coastal areas. The impact on the river and people who depend on it for their livelihoods were severe. The rush of tailings displaced river water which inundated low-lying areas, destroying crops and vegetable gardens and clogged irrigation channels supplying water to rice fields. The release left the Boac River virtually unusable. The effects of the incident were so devastating that a United Nations assessment mission declared the accident to be a major environmental disaster. The Tapian pit contained around 23 million metric tons of mine waste. Officials of the DENR (Department of Environment and Natural Resources) claimed they did not know of the presence of the drainage tunnel that measured 2.6 kilometres long and 1 metre wide which was located underneath the pit, which led to the Makulapnit and Boac river system. The toxic spill caused flash floods which isolated five villages, with populations of 4,400 people each, along the far side of the Boac river. One village, Barangay Hinapulan, was buried under six feet of muddy floodwater, causing 400 families to flee to higher grounds. Sources of drinking water were contaminated with toxins. Fish, freshwater shrimp and pigs were killed outright. Helicopters had to fly in food, water and medical supplies to the isolated villages. The inhabitants of 20 of the 60 villages in the province were told to evacuate. Aftermath The government estimates this toxic tailings waste killed P1.8 million worth of freshwater and marine life and P5 million milk fish fry. The 27-kilometer Boac river, which was the main source of livelihood for those who did not work for Marcopper, was declared unusable by government officials. After the disaster, Marcopper and Placer Dome closed all their mines. The government attempted to cover up the fact they had not enforced environmental laws throughout the years. The local residents in Marinduque have claimed they knew about the tunnel for almost 20 years. Evidence came to light that Marcopper knew of the leak in the drainage tunnel in advance of the accident, as there had been a long history of problems