One of Edmonton's most controversial pieces of public art has been vandalized, the city confirmed Saturday.

The Talus Dome — more casually referred to as the Talus balls — has been covered in green paint.

The Edmonton Arts Council manages the city's public art collection and will assess the damage and arrange for clean-up, but that may not happen until Tuesday, the city says.

The city became aware of the vandalism on the Talus Dome after pictures were posted on social media Saturday. (Scott Neufeld/CBC) So it's difficult to say how much the clean up will cost.No one reported the damage to Edmonton police or called it in to the city's 311 line. The city became aware of the vandalism after pictures were posted to social media, spokesperson Sarah Jackson said.

The sculpture near the Quesnell Bridge off the Whitemud freeway has been targeted in the past, but the city didn't know how many times.

Made up of about 1,000 hand-crafted stainless steel spheres, the sculpture refers to the "coexistence of the man-made and the natural," the city's website says.

Before the bridge was put in, talus — a slope or deposit of broken rock debris, formed naturally along the river valley.

The Talus Dome cost an estimated $600,000.