Thousands Of Birds Die After They Land On Poisoned Lake

It's like "700 acres of white birds."

Last week, a flock of about 10,000 migrating snow geese landed in Berkeley pit, a chasm created by decades of copper mining that is full of poisoned water.

Now many of the birds are dead.

"If they stay too long and ingest too much water we know it can be lethal," said Mark Thompson, manager of environmental affairs for the mining company Montana Resources, warned after the geese landed on November 28.

The lake has been filling with toxins, like sulphuric acid, since the copper mining stopped in 1982.

"This avoidable tragedy is yet another example of the lasting impacts of environmental destruction and one more reason to reject new proposed mines," Bethany Cotton, wildlife program director for WildEarth Guardians, told The Dodo.

Even though Montana Resources has been overseeing the pit, using loud noises and firearms to scare off birds from landing there, some call the pit "an ecological time bomb."

"When the groundwater flows through the old mine shafts, it reacts with oxygen to oxidize the sulfide minerals in the area which makes the water acidic," researchers at Montana State University found in 2012. "It drains into the Berkeley pit ... As the acid water travels through the ground it dissolves out metals such as arsenic, copper, cadmium, cobalt, iron, manganese, zinc and sulfate. All these toxic metals concentrate in the pit."

And this isn't the first time the toxic pit has taken lives. In 1992, over 300 geese died after they landed on the water.

The Environmental Protection Agency (EPA) is expected to review whether there was any negligence on the part of the company that could have been a contributing factor to the deaths. There are nine other open pit mines in the U.S.

"We call on authorities to do more to protect this year's migrating birds from the toxic waters and to investigate additional measures to employ in future years," Cotton said.

As for exactly how many birds have died, it's in the thousands - and people are still counting.

Thomson said it looks like "700 acres of white birds."

Montana Resources did not immediately reply to The Dodo's request for comment.