After several highly publicized incidences of bird deaths at the Berkeley Pit, a popular myth arose: migratory waterfowl are instantly killed if they land on water in the Berkeley Pit. In fact, hundreds of waterfowl land on the surface of the Berkeley Pit every month during migration seasons, and they typically fly off unharmed within a few hours, either on their own or through Montana Resource’s hazing activities, also known as the waterfowl mitigation program.
The 2002 Consent Decree recognizes that “birds exposed to Berkeley Pit water for less than 4-6 hours should not be at substantial risk.” If a bird is observed suffering from the effects of water toxicity, it is netted and brought on board the houseboat used to patrol the Pit lake. The bird is placed in a 5-gallon bucket of fresh water and brought to shore. It is then transported to a veterinarian or released into fresh water at the north end of the Yankee Doodle Tailings Pond; tailings particles settle out on the south portion of the pond, leaving clear, alkaline (or non-acidic) water in the north end which mixes with snowmelt runoff from upper drainages, resulting in very low concentrations of dissolved metals.
In November 1995, a flock of snow geese landed on the Pit lake. After several days of stormy weather and fog, 342 birds were found dead. In response to this incident, the two responsible parties for the Pit under federal Superfund law, Montana Resources and British Petroleum-Atlantic Richfield, also known as BP-ARCO, implemented a waterfowl mitigation plan, which was approved by the EPA and other agencies in May 1998. This program is aimed at locating waterfowl in the area and then inciting the birds to fly away. An observation station was set up overlooking the Pit area. This station is an enclosed building equipped with spotting scopes and spotlights for night viewing to locate, count and identify species of waterfowl on the Pit lake.
Montana Resources’ personnel make hourly observations for birds during the spring and fall migrations, while the pit is not frozen, and cut back to 5-6 observations per day during non-migratory seasons. A variety of devices are used to chase birds off the water and out of the Pit. From the observation station near the southeast rim of the Berkeley Pit, Montana Resources’ personnel use rifles and shotguns to scare birds into the air.
In addition, three Phoenix Wailers – high-tech devices that emit predator and electronic sounds – are located near the surface of the Pit lake to discourage birds from landing. A 22-foot houseboat, docked near the pump barge, is used for periodic excursions on the water to haze waterfowl that ignore other warnings. Not all types of birds react to hazing. Typically, most ducks, geese and swans will react immediately to the noises. Diver birds such as grebes and loons tend to go underwater as a natural defense mechanism when they are alarmed.
Normally, if birds are not hazed or disturbed, they leave the Pit area at nightfall. If a dead bird is found on the water or near the Pit, then the US Fish and Wildlife Service is contacted. They decide if an autopsy is necessary.
From 1995 through 2004, 75 birds were found dead. The advances made to deter migrating waterfowl from landing on the water or staying on the Pit appear to be working. Thousands of birds land and are hazed off of the Pit each year.
Though many local authorities decided that the 1995 incident was isolated and not likely to happen again with the safeguards that are in place, in October 2007, 37 birds, including ducks, geese, and one swan, were found dead at the Pit after a weekend of fog. It is unclear why mitigation activities failed to haze these birds away from the site, although the weather was almost certainly a factor. As the mitigation program continues, all involved continue to work to keep such incidents to a minimum.
The chart below, from the 2011 EPA Five Year Review Report on the site, shows Pit-related bird deaths from 2006-2009.