In many oil and natural gas fields, water occurs in the oil or gas reservoir and is extracted along with the petroleum particularly in older wells. Water or steam is also used in some wells to enhance the extraction of oil. During production, the process of separating oil and produced water using heat treaters is often ineffective. Production skim pits or open-topped tanks are used to further separate oil from produced water. The produced water is either discharged into surface waters, injected underground, or transported to a commercial oil field waste disposal facility. Commercial oil field waste disposal facilities also pose significant risks to wildlife. Reserve pits used during drilling operations to store drilling fluids can also cause bird and wildlife mortality if they contain visible sheens or oil on the surface. Flare pits, earthen pits constructed below flare stacks used to vent hydrogen sulfide gas from production wells can also cause bird and wildlife mortality if they contain visible sheens or oil on the surface. Exposed oil in load line containers, drip buckets, dehydration tanks or tubs, and well chemical spill containment devices at oil and gas production facilities can also attract and entrap migratory birds. Some oil operators still continue to use colored flagging at oil skim pits and reserve pits to deter birds. Flagging is not effective at preventing wildlife mortality in oil pits.
Production Skim Pits
Commercial or Centralized Oil Field Wastewater Disposal Facilities
In 1997, the U.S. Fish and Wildlife Service (Service) estimated that 2 million migratory birds were lost each year to oil pits throughout the United States. Since 1997, many oil operators have taken measures to prevent migratory bird and other wildlife mortality in oil field waste pits. In 1997, the U.S. Fish and Wildlife Service (Service) estimated that 2 million migratory birds were lost each year to oil pits throughout the United States. Since 1997, many oil operators have taken measures to prevent migratory bird and other wildlife mortality in oil field waste pits. Currently, an estimated 500,000 to 1 million birds are lost annually in oil field production skim pits and centralized oilfield wastewater disposal facilities (Trail, P. 2006. Avian mortality at oil pits in the United States: a review of the problem and efforts for its solution. Environmental Management. 38:532-544).
- Skim ponds are a fatal attaction to mirgratory birds
- Birds, bats, and other wildlife mistake these oily pits for wetlands
- Birds landing on waste pits can get covered with oil
- Oil can weigh birds down and cause them to drown
- Many bird deathes go undetected becausethe carcasses sink to the bottom of the pits
- Oil destorys the feathers' ability to insulate the birds resulting in death from heat or cold stress
- Even a light sheen on the water surface can be deadly. Oil on the feathers of female bird can be transferred to their eggs back at the nest, killing the embryo.
- Small amounts of oil applied externally to the egg shells are extremely toxic to embryos
- Some birds become victims of pits when they feed on insects trapped in oil covering the surface of the water.
- Waterfowl are not the only victims. Songbirds are attracted to pits by insects entrapped in the oil. Hawks and owls in turn become victims when they are attracted by struggling birds or small mammals.
- The Migratory Bird Treaty Act (16 USC 703-711) prohibts the "taking" of migratory birds
- Taking cam include the following activities resulting in migratory bird mortalities: exposed oil waste pits, hazardous materials spills, and oil spills
- Eagle mortalities cause by oil pits is a violation ofthe Bald Eagle Protection Act
- Mortality of threatened and endangered birds or other wildlife in oil pits is a violation of the Endangered Species Act
It doesn't take much oil to entrap songbirds such as this horned lark. Cleanup of all spilled oil is essential to prevent wildlife mortality.