Question: Which Central Appalachian coal producer was responsible for a spill that dumped 306 million gallons of slurry into tributaries of the Tug Fork River? 

Context paragraphs:
Morris J. Berman oil spill: The Morris J. Berman oil spill occurred on January 7, 1994, when the "Morris J. Berman", a single-hull 302-foot-long barge, with the capacity to carry more than 3 million gallons of oil, collided with a coral reef near San Juan, Puerto Rico, causing the release of 750,000 gallons of heavy grade oil.  The spill affected the tourism and fishing industries as well as wildlife along the shores of Puerto Rico, Isla de Culebra, and Isla de Vieques.  The spill had major long-lasting impacts on the biological and natural resources of the entire Puerto Rican area.  This spill was also the first to occur in U.S. waters after the passing of the Oil Pollution Act of 1990.

Automotive oil recycling: Automotive oil recycling involves the recycling of used oils and the creation of new products from the recycled oils, and includes the recycling of motor oil and hydraulic oil.  Oil recycling also benefits the environment: increased opportunities for consumers to recycle oil lessens the likelihood of used oil being dumped on lands and in waterways.  For example, one gallon of motor oil dumped into waterways has the potential to pollute one million gallons of water.

Kingston Fossil Plant coal fly ash slurry spill: The TVA Kingston Fossil Plant coal fly ash slurry spill occurred just before 1 a.m. on Monday December 22, 2008, when an ash dike ruptured at an 84 acre solid waste containment area at the Tennessee Valley Authority's Kingston Fossil Plant in Roane County, Tennessee.  1.1 e9USgal of coal fly ash slurry was released.  The coal-fired power plant, located across the Clinch River from the city of Kingston, uses ponds to dewater the fly ash, a byproduct of coal combustion, which is then stored in wet form in dredge cells.  The slurry (a mixture of fly ash and water) traveled across the Emory River and its Swan Pond embayment, on to the opposite shore, covering up to 300 acre of the surrounding land, damaging homes and flowing up and down stream in nearby waterways such as the Emory River and Clinch River (tributaries of the Tennessee River).  It was the largest fly ash release in United States history.

Martin County coal slurry spill: The Martin County coal slurry spill was an accident that occurred after midnight on October 11, 2000 when the bottom of a coal slurry impoundment owned by Massey Energy in Martin County, Kentucky broke into an abandoned underground mine below.  The slurry came out of the mine openings, sending an estimated 306,000,000 gal of slurry down two tributaries of the Tug Fork River.  By morning, Wolf Creek was oozing with the black waste; on Coldwater Fork, a 10 ft wide stream became a 100 yd expanse of thick slurry.

Tug Fork Wildlife Management Area: Tug Fork Wildlife Management Area (WMA) is located about 10 miles northwest of Welch, West Virginia in McDowell County.  Tug Fork WMA is located on 2165 acre of steep terrain along hills above the Tug Fork River.  The WMA is heavily forested, primarily with mixed hardwoods and yellow poplar/black cherry forests in the coves.  The WMA is accessed from U.S. Route 52 at Premier.  Several tracks and jeep trails provide walking access into the Tug Fork WMA from U.S. Route 52.

Williamson, West Virginia: Williamson is a city in Mingo County, West Virginia, United States, along the Tug Fork River.  The population was 3,191 at the 2010 census.  It is the county seat of Mingo County, and is the county's largest and most populous city.  Williamson is home to Southern West Virginia Community and Technical College.  The Tug Fork River separates Williamson from South Williamson, Kentucky.

Sludge (film): Sludge is a 2005 documentary film by Appalshop filmmaker Robert Salyer chronicling the Martin County Sludge Spill that was an accident that occurred after midnight on October 11, 2000 when a coal sludge impoundment in Martin County, Kentucky, broke through an underground mine below, propelling 306 million gallons of sludge down two tributaries of the Tug Fork River.  The movie documents the continuing story of the Martin County disaster, the resulting federal investigation, and the looming threat of coal sludge ponds throughout the coalfield region.

Cello Energy: Cello Energy was an Alabama biofuels company beset by fraud allegations.The company proposed to produce energy from cellulosic ethanol.  In 2010, the United States Environmental Protection Agency projected the company could produce 70 million gallons of cellulosic diesel before reducing their projections to 5million gallons and then removing the company from supplier listings in 2011. Cello Energy filed for bankruptcy in 2010.

Dry Fork (Tug Fork): The Dry Fork is a 47.7 mi tributary of the Tug Fork, belonging to the Ohio River watershed.  The river is located in McDowell County, West Virginia and Tazewell County, Virginia, in the United States.  The mouth of the Dry Fork into the Tug Fork is located at Iaeger.

Massey Energy: Massey Energy Company was a coal extractor in the United States with substantial operations in West Virginia, Kentucky and Virginia.  By revenue, it was the fourth largest producer of coal in the United States and the largest coal producer in Central Appalachia.  By coal production weight, it was the sixth largest producer of coal in the United States.

Supporting paragraphs: Martin County coal slurry spill Massey Energy
Answer: Massey Energy