Colorado residents fighting the artist Christo's dream of draping the Arkansas River with fabric are asking a federal appeals court to throw out permission for the project.
The Bureau of Land Management signed off on the plan to drape 6 miles of fabric panels along 42 miles of the river, which would take about two years to install.
The lawyer for opponents, Michael Harris, told judges Wednesday that the agency violated its own plans for protecting the sensitive environment by allowing what he called an "industrial scale project."
The BLM acknowledges that the work could potentially harm bighorn sheep in the area but says it has required Christo to provide monitoring of the animals and other kinds of mitigation.
It says the project will draw visitors and enhance their enjoyment of the area.