The coal ash spill near Harriman, Tenn., could have been avoided if TVA had repaired two small holes in the dams that appeared years earlier.

According to the Associated Press, TVA ignored two small leaks that could have provided a warning years before a coal ash pond collapsed, flooding a neighborhood with a billion gallons of sludge.

Jack Spadaro, a retired mining engineer who investigated a 1972 coal waste dam break that killed 125 people in West Virginia, said states have done a poor job monitoring huge ponds of coal ash, which aren’t regulated by the federal government.

Three homes were destroyed and 42 parcels of land damaged when a sludge pond at the Tennessee Valley Authority’s Kingston Steam Plant collapsed Dec. 22.

At the Kingston plant, two small leaks in 2003 and 2006 caught the attention of Tennessee’s Department of Environment and Conservation, which asked TVA to provide additional details on the water going into the ponds but didn’t require a new storage system.

Tennessee uses solid waste landfill regulations for ash ponds, even though the substance in them — a mix of water and fly ash, a byproduct of coal-fired power plants — behaves more like a liquid when it spills and contains toxic chemicals including mercury and arsenic.

Read more here.