A federal judge has given the green light for a Christo and Jeanne-Claude project that would hang almost six miles of silvery fabric over stretches of the Arkansas River in Colorado, between Cañon City and Salida. Local activists oppose the project.

The ruling, delivered on Friday, found that federal officials had complied with environmental laws in approving the project.

A Cañon City–based grassroots organization, Rags Over the Arkansas River, or ROAR, filed a lawsuit in 2012 seeking to block the art installation on the grounds that the project would endanger local wildlife, including fish and bighorn sheep. The group also voiced concerns over public safety, increased traffic on nearby US 50, and tourism.

Featuring 5.9 miles of panels hung in eight sections over a 40-mile stretch of the river, the installation would be in situ during a two-week period in August. At that point in the year the river is generally quite calm, affording rafters the opportunity to enjoy the fabric canopies overhead in a leisurely manner.

Christo and his late wife and partner Jeanne-Claude conceived the piece in the 1990s and selected the Arkansas River after exploring 89 potential rivers in seven states.

The artist was pleased by the court decision, telling the Pueblo Chieftain that “we have one lawsuit in state court still outstanding, but today we took a very significant and important step forward in realizing Over the River.” Christo expects the project to take a full three years to come to fruition, meaning it will likely be realized in 2018 at the earliest.

Although the ruling is a setback for ROAR, the group is not about to give up the fight. “We are still reviewing the judicial opinion and considering other steps to prevent the project from ever being allowed to happen, including the possibility of an appeal,” spokesperson Joan Anzelmo told the Chieftain. The group believes that technical compliance with laws such as the Federal Land Policy and Management Act (FLPMA) and the National Environmental Policy Act (NEPA) does not preclude the project from being environmentally destructive.

On the official website for the project, an FAQ promises that “the construction and viewing periods have been carefully scheduled around breeding and nesting seasons. Construction buffer zones will be created near potentially active eagle nests and around designated sheep areas.” In addition, “Christo will entirely fund a new wildlife corridor that the Colorado Division of Wildlife has long sought, thus providing an improvement for bighorn sheep that will last long after Over The River is removed.”