Each year, Gray whales set out on one of the longest migratory journeys on the planet: a nearly 13,000-mile swim from their feeding grounds in Alaska to the warm waters of Baja California Sur in Mexico.

In Baja California Sur whales birth and raise their calves - after which they turn around and swim back again.

Experts estimate that by the time a Gray whale turns 50 it has traveled the distance from the earth to the moon and back.

But this impressive, 50-foot mammal and its migratory feat are threatened by one of the world's first marine phosphate mines.

If the project gets the green light, the mine could gravely damage the environment the Gray whale needs to breed and nurse during winter months.

The scope of the threat to whale populations became all too clear in late February when more than 2,600 Gray whales arrived at the San Ignacio and Ojo de Liebre lagoons in Baja California Sur, very close to Ulloa Bay.

This was the highest number of whales recorded in the past 19 years. The whale migration provides an important source of income for local families who depend on tourism dollars from whale watchers.

Clearly, just the place for a 225,000 acre undersea mine

Yet it's precisely in this area near Ulloa Bay that the American company Odyssey Marine Explorations intends to start the 'Don Diego' phosphate mine. The proposed mine would include five work sites in an area of more than 225,000 acres.

Each site would be exploited for 10 years, resulting in a 50-year-long project. The goal is to extract 350 million tons of phosphate sand from the marine floor-a quantity that would fill Mexico City's Aztec Stadium 264 times.

Gray whales, as well as Humpback and Blue whales and Loggerhead turtles that live in or pass through the zone, depend on sound to communicate, stay together and find food. The Don Diego project will use dredging to collect the phosphate sand, producing a lot of noise in the process.

Even the company's own environmental assessment concedes that the mine could create a "modification of vocal behavior or surprise reaction" in the whales. The noise could jeopardize the survival of the whales by causing changes in their behavior and migration route, and it could also disrupt mothers feeding their calves.

Moreover, large boats will dredge the seabed to extract sand, but in the process they will also upend living organisms. The dredged material will be separated to obtain phosphate, and the leftover material dumped back into the sea.

The sediments returning to the ocean may contain high levels of toxic elements such as uranium and thorium, which are exposed during the phosphate-separation process. These toxins may be consumed by fish that then arrive on our tables, making phosphate mining a potential source of radioactive contamination.

Mexico's chance to prove itself a wise guardian of the oceans

In September 2014, Odyssey presented its environmental impact assessment to Mexico's Secretariat of Environment and Natural Resources. AIDA, the Interamerican Association for Environmental Defense, presented comments on the Don Diego environmental assessment before the secretariat, spotlighting the ecological reasons the project should be shelved and requesting more detailed information from the company.

Last month the Commission for Environmental Cooperation (CEC), which includes the United States, Mexico and Canada, voted against a request that the nations investigate whether Mexico appropriately considers environmental risks of proposed projects with coastal impacts.

However the question is certain to recur at CEC's 12th Council Session which is taking place in Boston next month, 14th-15th July - all the more so if civil society draws the matter to the Council's attention.

Now, Mexico has the opportunity to demonstrate that it is in fact a good steward of the oceans by rejecting the Don Diego plan. A pristine marine area favored by tourists, sensitive ecosystems and the continued well-being of the Gray whale depend on the decision the Mexican government is about to make.

In places such as Namibia and New Zealand, after analyzing similar projects, governments revoked permissions or declared a moratorium on phosphate mining until the industry can show it does not cause grave environmental harm.

The Mexican government should follow their example and err on the side of caution.

Action: Ask CEC to reconsider its decision not to investigate the risks of Mexico's coastal projects via Facebook and Twitter.

Action: Ask Odyssey Marine Explorations to desist from the project via its website, Facebook and Twitter.

Haydée Rodríguez is an environmental law attorney with a master's in environmental science and public policy from Columbia University, New York. Based in San José, Costa Rica, Haydée has been working for AIDA on marine protection, freshwater and mining issues since 2013.

This article was originally published by EarthJustice.