For the past month, a broken oil well in Colombia has been pouring crude oil into important waterways in the state of Santander. Officials say that the spill is now under control, but as Elaina Zachos reports for National Geographic, the environmental disaster has caused the deaths of 2,400 animals, damaged 1,000 tree species and forced residents to evacuate from the area.

The spill began on March 3 at the Lizama 158 oil well, which is operated by the state-owned company Ecopetrol, according to Jacqueline de Klerk of The City Paper, Colombia’s largest English-language newspaper. Oil has since seeped into the Lizama and Sogamoso rivers, and according to Zachos, local media is reporting that the contamination has reached the Magdalena river, a major waterway that stretches about 950 miles through the western part of the country.

It remains unclear how much oil has been spilled; Ecopetrol says 550 barrels, but Colombia’s National Agency of Environmental Licenses (ANLA) says that 24,000 barrels have now leaked their contents through miles of the rivers.

Around 1,250 animals have been rescued from the affected areas, but thousands more—among them cattle, fish, birds and reptiles—have died. The spill has also depleted the livelihoods of fishing communities along Liazma and Sogamoso rivers, and a number of residents are being treated for dizziness, headaches and vomiting.

“I have practically nothing to eat, we have lived through the river all our lives and the contamination has already reached the Magdalena,” resident Elkin Cala tells the Colombian television station Noticias Uno, according to Lorraine Chow of EcoWatch.

Ecopetrol said on Saturday that the spill had finally been brought under control, according to Adriaan Alsema of Colombia Reports. But the company’s handling of the crisis is now facing intense scrutiny. In the wake of the spill, media reports revealed that the Controller General’s Office had advised Ecopetrol in 2015 to abandon its wells in the Lizama region. A 2016 government audit found that 30 of the company’s abandoned wells were in danger of breaking.

Felipe Bayón, the president of Ecopetrol, has said he believes that seismic activity—and not technical failures—caused Lizama 158 to crack, reports The City Paper’s de Klerk. Santander does experience a frequent seismic tremors, but according to Alsema, Colombia’s Prosecutor General’s Office has launched a criminal investigation into claims that neglect lead to the spill. The country’s Environment Ministry has also said that it may impose sanctions on Ecopetrol, which falsely claimed to have stopped the spill one day after it began.

ANLA, the environmental agency, has said that it does not know how long it will take for the region to recover from the devastating crisis.

“As the vegetation is dying, the area has to go through a process of rehabilitation,” ANLA official Claudia Gonzalez tells local newspaper La Vanguardia, according to Alsema. “The banks of the gorges have to be recovered again and the habitat of the species of the area has to be improved.”