Highly contentious plans to open up land in Colombia’s eastern plains for oil exploration are off the table.

On Tuesday afternoon, the National Authority of Environmental Licenses (ANLA) announced that it had revoked a license granting Hupecol, a Texas-based firm with offices in Colombia, the right to drill exploratory wells in an area near the municipality of La Macarena.

“We have revoked the license … which granted Hupecol exploration rights for hydrocarbons in the area dubbed ‘Serranía,’” said Fernando Ireguí, director of ANLA in a press conference Tuesday.

The area in question is relatively small — about one-fifth the size of Bogotá — but its proximity to national parks, small municipalities and the Caño Cristales river, make it a highly sensitive zone.

Caño Cristales, sometimes known as the River of Five Colors, is of particular concern. The unique waterway, marked by vibrant red, green, blue, black and yellow patches of algae and aquatic plants, has frequently been referred to as one of the world’s most beautiful.

According to Ireguí, the revocation stemmed primarily from a new, multi-year environmental impact study presented last week by Cormacarena, an autonomous regional organization dedicated to sustainable development in the affected area.

During the press conference Tuesday, Ireguí explained that Colombian environmental authorities are obligated to take the Cormacarena study into consideration before exploratory activities can continue in the area.

The block previously up for oil and gas exploration lies roughly 60 kilometers from Caño Cristales. However, it sits much closer to rivers and streams that stem from the same watershed as the iconic river and fewer than five kilometers from the border of the Tinigua National Park.

At the center of the controversy is United States-based firm Hupecol. The hydrocarbon exploration and drilling company has operated in Colombia for nearly two decades, and not without previous tensions.

“The licensing process for this block has not been easy,” said Hupecol representatives in a statement released last week. “Hupecol has complied with and will continue to rigorously comply with everything established by the law and by environmental authorities.”

According to Hupecol, the first steps toward oil exploration near La Macarena were taken in 2008, when the National Hydrocarbon Agency (ANH) opened up the block to potential seismic activity and the drilling of exploratory wells.

Security concerns delayed any significant progress until 2013, at which point Hupecol representatives began working with local community and government organizations to license work in the area. A final license was officially granted by ANLA in March.

According to ANLA, no other licenses are currently in the works for the area.

President Juan Manuel Santos and Colombia’s Ministry of the Environment had called on ANLA to revoke the Macarena license, at least until protections for the Caño Cristales area could be guaranteed.

On Wednesday, Ministry of the Environment Director of Communications Natalia Ochoa explained that ANLA’s actions had fulfilled the ministry’s request.

“We don’t have any position other than that which we took last week,” she said. “This cycle is closed and the ministry is ready to move on.”